Game Breaker/Video Games/Role-Playing Game/Pokémon

Game Breakers in the Pokémon series.

General Maingame

 * One strategy that works very well in almost any Pokémon game is simply using only one Pokémon in battles. While you're supposed to be using a balanced team to counter the Pokémon that are strong against your starter, by simply using the same 'Mon over and over, it becomes so powerful that even super-effective hits deal almost no damage (and that's assuming they manage to hit you at all). Not until Pokémon Black and White was this strategy finally nerfed; your experience gains are based on the level difference between your Pokémon and the Pokémon you're fighting, so training just one Pokémon isn't really viable, as they'll be getting crap for Experience in no time.
 * It's important to note that you WILL get a lot more EXP at the same level though, making getting early levels much easier. And later in the game, you can still be so overleveled that you don't NEED more... It's not uncommon to see a level 43 or so Emboar (usually used because it has a great movepool and decent all around offenses) before the fourth gym, when the gym leader uses level 30 at the most.
 * It's not quite as nerfed in Black & White as it might seem. Thanks to the fact that you get the Lucky Egg for free roughly half way though the game (which in itself could be considered a minor Game Breaker), the boosted EXP makes it quite possible to plow though everything with one high-leveled Pokémon.
 * The single easiest way to get through any game is by having a friend who has already beaten the game and is willing to trade powerful mons. The first Gym Leader's level 15 or so Pokémon aren't exactly a match for a level 90 juggernaut, are they? To attempt to prevent this, the designers include the badge system; Pokémon not caught by the player will usually ignore them (doing things like sitting around, even sleeping in the middle of the fight) if they are above the level designated by the player's badges. The problem is that: 1. the Pokémon only has to listen to the trainer once, while in the meantime the opponents aren't capable of doing anything at all thanks to the super-Pokémon's ridiculous defenses, and 2. the badge system seems to think that the Trainers are much stronger than they are (for example, getting the fourth badge makes a traded Level 50 Pokémon listen to you, whereas the final boss has Level ~60 Pokémon in an average game.)
 * Even easier is if you have a friend further in the game who has a bit of patience. Trade them your Mons and have them level them up on the higher-leveled Pokémon late in the game (along with the boosted exp for trading), and then trade back when they're sufficiently leveled. Then you won't even have to worry about the Pokémon ignoring you occasionally, as your own will listen to you no matter which badges you have.
 * The series' original game breaker, and to this day one of the most dreaded, is Double Team. This move (and the very similar Minimize) increases the user's evasion - on the first use, all moves have 3/4 of their normal chance of connecting, the second use drops this to 3/5, and can continue until accuracy is 1/3 of the usual value. And when it was introduced, only one move could counter its usage - the underwhelming Swift. If an opponent had the chance to buff their evasion enough, or could heal on top of that (such as early top tier favorites Alakazam, Starmie, or Mewtwo), you basically had to hope to get extremely lucky if you wanted a chance to win. Even with a proliferation of ways around it (10 different moves guaranteed to hit, plus a few other ways to neutralize it), the effects of evasion are feared so much that banning the two moves guaranteed to raise it is perhaps the most common house rule called, items giving one level of increase are considered overpowered, and things that have a chance of increasing it (the move Acupressure and the ability Moody) are also sometimes called game breakers themselves. And it is ridiculously easy to get, to the point where the full list of fully evolved Pokémon that can't learn Double Team at all is as follows: Ditto, Unown, Wobbuffet.
 * There's also Minimize, which at first it was "Double Team, but with more uses and only a few can learn it". Then Pokémon Black and White make it boost evasion twice as fast as Double Team. Ow. It's just as banned as Double Team at least, but still.

First Generation

 * In the first generation of games, the entirety of Psychic-type Pokémon were overpowered, as they only had a weakness to types of attack that did below-average damage even after being doubled, and there were very few Pokémon with the stats to use moves of these types anyway (and due to a bug, one of those types actually didn't affect Psychic-type at all, rather than do double damage). And also by the fact that in Generation I, the most common type was the Poison-type (which is weak to Psychic-type), with 33 members, just narrowly beating out the ever-common Water type (32 of the Generation I Pokémon.) In later games, the Poison-type Pokémon count fell to the back so far that it was tough to remember why Psychic was ever such a powerful type to begin with. The Psychic-type advantage was made worse by the fact that the stat Special governed both Special Attack and Special Defense. This meant that Pokémon with high Special, such as Psychics, were much more useful than Pokémon with low Special, such as Fighting. This was fixed in later generations by separating them. Psychics were so overpowered in Generation I that Jolteon was frequently used for the sole purpose of countering Psychics, simply for the fact that it learns the move Pin Missile.
 * Even among Psychic types, Alakazam deserves special mention; its base Speed was beaten only by four other Pokémon (Electrode, Jolteon, Aerodactyl, and Mewtwo), in games where the Speed stat was also used to determine critical hits, and its base Special was just insane. If you knew what you were doing, you could get one as soon as you got to the second gym, and basically have it nuke the entire game single-handedly. And to make matters much worse, after beating the game, you could go to the Bonus Dungeon and catch Mewtwo, an Olympus Mon that was everything that was great about Alakazam taken Up to Eleven - especially with its Amnesia move which doubled its Special every use. To quote Smogon, "RBY Mewtwo is the single most powerful Pokémon in any generation. Nothing even comes close to the raw destructive power of this thing."
 * Honorable mention must go out to the Legendary Pokemon Mew. If you knew what you were doing, you could get a Mew (or two even) as soon as you got to the second gym. And if you remember the days when one had to either attend a limited-time-only Nintendo Event or input long, tedious strings of code on a gameshark or an action replay (which had to be bought separately), there's a certain satisfaction in being able to obtain the above-mentioned Alakazam's inferior pre-evolution and then swap it for the fantastically overpowered, legendary analog with very, very little effort, and then basically have it nuke the entire game single-handedly. Hurray for the Mew Glitch!
 * Although, Psychics in general are ridiculous, another special mention is to Exeggutor who has good stats, nice sets of resistance (and some weaknesses that, back in Gen 1 aren't too well developed, making it some sort of Fake Balance) and nice move pools, including Explosion, Sleep Powder, and Stun Spore. To put it simply, in a metagame with such powerful threats, a status problem move will be very brutal to deal with. Exeggutor didn't have the speed of Alakazam, but its insane movepool made it a really frustating mon to deal with.
 * Speaking of gen 1, one Pokemon stand amongst the rest, being considered the King of OU, not a psychic, but a Badass Normal, literally: Tauros. It has solid stats (for the time) and nice move pools that allowed it to deal with most threats in the metagame. However, by the time, normal is, without a doubt one of the best offensive and defensive types. Fighting moves are rare, and it is only resisted by Rock, which Tauros can cover with Blizzard (listed above), and at the time, Normal had the no recharge after Hyper Beam, which got downright brutal combined with the fact that Tauros was pretty fast as well. The best part, however, is the fact that if you mispredict the Hyper Beam, it can use Body Slam which paralyzes 30% of the time. It was so ridiculous that some considered the introduction of Foretress and Skarmory by Generation 2 is mostly for this beast.
 * Also, another Badass Normal was Persian mainly because it was easy to obtain (at least in Blue Version), had great attack and speed, was very versatile, and had a great move set, which included Pay Day (so you would never run out of money again) and Slash (which always landed a Critical Hit in this game) and both moves were normal, so they got STAB as well. The only thing that could slow it down or stop it were Rock and Ghost Pokemon which were a small amount of the overall Pokemon population back then, and could be countered with Blizzard. Everyone else was susceptible to Slash considering it was 70 base power and 100 base accuracy plus STAB (1.5x) plus critical hits (2x). In other words, a Persian's slash was equal to 210 base power and 100 base accuracy, and unlike a lot of moves at that power, it had a lot of pp (power points), so it could keep spamming Slash until it eventually won the battle.
 * One mustn't forget Missingno. in Red and Blue. It's complicated to explain how to do it, but basically you can use a glitch to duplicate all your items, including the Master Ball. So you can catch ANY Pokémon with ease. Or duplicate Rare Candies, and just spam your way to high levels (though your stats suffer somewhat). Or you can get infinite amounts of certain TMs and items, and can sell for boatloads of money or teach them to everything on your team. One must be careful when using it, though - it can become a Game Breaking Bug if you're not careful.
 * Pokémon Stadium. Go to Pika Cup with a Level 20 Charmeleon, Dragonair or Arcanine that knows Dragon Rage and see what happens. It got nerfed on Stadium 2's Little Cup, though, where SonicBoom and Dragon Rage will always miss.
 * While not quite as much so in the maingame, the competitive multiplayer of the first generation was largely broken by the presence of the Blizzard attack. On top of being the most powerful Ice-type attack in the game and having 90% accuracy, it had a 30% chance of inflicting the Freeze condition, which the only cure for was to use an item. To those not familiar with competitive multiplayer, neither player can use any items, meaning a frozen Pokémon was basically dead. This made battling at a high level become less "who has the better team and strategy" and more "who gets luckiest with Blizzard's freeze". The second generation nerfed this hard, as frozen Pokémon can now randomly defrost, and Blizzard has only a 70% accuracy rate and a 10% freeze rate, causing the weaker Ice Beam to become the Ice-type attack of choice.

Second Generation

 * Snorlax. The Special split in Generation 2 heavily buffed Snorlax's Special Defense, which coupled with its already insane HP made special attacks virtually useless against it. Combine this with the new Curse move, which buffs both Attack and Defense at the cost of speed (which doesn't matter for Snorlax who is among the slowest Pokémon in the game anyway), and the Rest move, which fully restores its HP at the cost of missing two turns (during which the buffed Defense means that even Fighting-type attacks do virtually nothing), and watch in awe as Snorlax proceeds to wipe out the entire enemy team between Return and Earthquake. Oh, did they try to poison or burn you? Rest again and laugh it off. Snorlax is arguably the sole reason that Gengar got Levitate in Generation III (making it immune to both Return and Earthquake).
 * Actually, it could be argued that Snorlax would have been Uber had the online Pokémon competitive communities been developed as we know them today (see Garchomp and Salamence in Fourth Generation below), this game-breaking moveset now known as Curselax was even more scary taking to account the HUGE ammount of moves capable of being learned by Snorlax, making it more unpredictable (as it is a Normal-type Pokémon, and Normal-types usually can be taught a ridiculous pool of moves many of which doesn't make sense in 'Mons like Raticate, ranging from Shadow Ball to Blizzard). And that isn't taking into consideration that a smart player WOULD FIND his/her ways to use Curse whenever possible (which being Snorlax is pretty easy, as it walls every Special Attacker under the horizon). To put it in words, whenever an opponent's Special Attacker reared its head into the battle, the player could simply bring Snorlax, start to use Curse not caring if the opponent switched his/her 'Mon out or fruitlessly stayed in and attacked Snorlax with Special attacks, and would outright destroy the opponent's team. Late-game, when the few 'Mons capable of defeating Snorlax (or at least, making it switch out) were cleaned, this spelled doom. Hell, the thing was more like a Blissey with ACTUALLY USABLE Attack's stats (and how!). To quote Smogon: there really isn't such a thing as a complete Snorlax counter. Then again, as most things related to tiers and controversial powerful Pokémon, Your Mileage May Vary.
 * And then came the Atmacune (Suicune with Curse/Rest/Return/Roar) moveset. Not only does it crush everything except Ghosts, but Roar forces Snorlax to flee AND (due to its programming) causes enemy attempts to Roar or Whirlwind Suicune away ALSO fail. There's a reason why Curse went from "used by everyone" in Generation II to "used by almost nobody" in Generations III and IV...
 * As of the 4th Generation games, the Curselax strategy has become significantly weaker and more difficult to use effectively thanks to the physical/special move split (although it can now use physical Crunch (to hit Ghosts) and Fire Punch (to hit Steel-types)). It's still somewhat viable though, but a lot of powerful physical moves can 2- or 3HKO it if the attacker switches in on its first Curse, and Pokémon such as Skarmory have access to Whirlwind and Roar to make it switch out. The 5th Generation games aren't seeing a lot of Snorlax use, as its formerly insane defenses are much easier to break thanks to generally more powerful mons lurking around.
 * Skarmbliss - the combination of Blissey and Skarmory on the same team - is one of the most infamous defensive cores in Pokémon. Skarmory has fantastic physical defense and resists every physical type except Rock and Fighting (plus an immunity to the ever-present Earthquake), while Blissey just has absolutely ridiculous special defense to the point where even in Uber matches it's one of the premier special walls. Chipping away at them generally isn't an option, because Skarmory is happy to use Whirlwind to force the opponent to switch out and can Rest if things are starting to look bad, and Blissey can just heal itself. By combining this with a third Pokémon that has the Spikes move, which hurts anything that isn't Flying-type that switches in (and yes, Skarmory's Whirlwind counts for this), and giving Blissey Toxic to force even more switches while chipping away at the opponent's health, these two can easily stall an entire team to death. The third generation nerfed this by introducing Pokémon capable of breaking the core without needing to switch (such as Blaziken), a Pokémon with a move pool that is huge enough that it can run a specialized set to break both (specifically Tyranitar and the famous Tyraniboah set that was actually considered the set that ended the Skarmbliss era) and giving a few Pokémon an ability that prevents one of them from switching out (Magneton and Dugtrio come to mind), though it's still considered one of the best defensive cores in the game.

Third Generation

 * The introduction of Abilities in Generation III did a lot to change the viability of certain Pokémon, but none more so than Wobbuffet. In the previous generation when Wobbuffet was introduced, it had terrible stats with the exception of HP (which was near the best in the game), and four moves: Counter, Mirror Coat, Safeguard, Destiny Bond. Counter and Mirror Coat took any damage dealt to Wobbuffet that turn and dealt double back to the opponent; Counter only works on physical moves, Mirror Coat only on special moves. Safeguard blocks all status moves, while Destiny Bond is straightforward Taking You with Me...except that Wobbuffet didn't have the Speed to use these moves before the opponent hit it, basically making them useless and forcing Wobbuffet to rely purely on its counters, which the opponent could easily switch out of. Joke Character, simple as that. And then Ruby and Sapphire gave Wobbuffet the Shadow Tag ability, which prevents the opponent from switching, AND introduced its baby form Wynaut, adding three moves to its movepool, one of which was Encore. This move forces the opponent to use their last move around 5 times in a row. Forcing the opponent to repeat their moves while preventing them from switching is possibly one of the most sadistic strategies Pokémon has to offer. If the opponent decided to play around this by using a non-damaging move like Swords Dance, Wobbuffet would happily switch out to another party member, which then had a free turn to set up any stat buff it wanted, while the opponent was still Encored and helpless. And by giving Wobbuffet the Leftovers item, which gives it 1/16-of-maximum-HP recovery every turn (note again that Wobbuffet has near the best HP in the game), it could stay on its feet almost indefinitely. All of this gives Wobbuffet the dubious honor of being the first non-legendary Pokémon to be banned from competitive play; not even the aforementioned Generation II Snorlax could get this far (though it did come very close). And the second? Wynaut. Wobbuffet's baby form.
 * Wobbuffet and Wynaut were banned for good reason at least. Imagine this: two trainers both send out Wobbuffet. Both of them are equipped with Leftovers (a common equip for the high-HP, low defense Wobbuffet before Wobbuffet was banned). Neither one can attack on its own except for Struggle (and remember, Wobbuffet also has rock-bottom attack power), and last but not least, neither one can switch out thanks to Shadow Tag. Literally, a battle no one can win. The only way for either Wobbuffet to triumph is to get something like 30 critical hits in a row. Thankfully, in Diamond and Pearl, it was changed so that any Pokémon with Shadow Tag could switch out from another Pokémon with Shadow Tag. This gets rid of the dreaded Wobbuffet vs. Wobbuffet scenario (for the most part), and also allows the very few Pokémon with Trace (an ability which copies the opponent's ability) to get away as well. They also added a couple of moves to either force a switch or neutralize an ability in some way, giving a handful of ways (if you prepare them) to escape. Struggle was also changed drastically; the recoil is now 25% of the user's maximum HP, rather than a percentage of the damage done. It's still entirely possible to get stalled out in the Generation III games though.
 * Wobbuffet and its ability actually caused Nintendo to change the rules of official tournaments. Originally, tournaments simply had rules against use of cheat devices and poor sportsmanship. Upon Ruby and Sapphire being released, they simply banned use of Leftovers on Wobbuffet (for the reasons mentioned above). Finally, they changed the format of all subsequent tournaments to doubles, where Wobbuffet is mostly dead weight (it'll prevent opponents from switching out, but since it can't force opponents to target it, an opponent will focus their attacks on Wob's partner, rendering its countering abilities moot while forcing its partner to fight two-on-one).
 * Ruby and Sapphire's main game was easily broken by the Pickup ability in general, and Zigzagoon in particular - since Zigzagoon is otherwise a ComMon, you can very easily catch four or five of the things almost immediately without grinding for money. This ability gives the user a 10% chance of finding an item after every battle - more than it sounds, as over the course of the game you'll be battling a lot, and this is per Pickup user. The items in question include Ultra Balls, Revives, Nuggets, Full Heals, Full Restores, even Rare Candies, and that's before you even get into the "rare" items category. And this is from the beginning of the game. Before long this means more items and more money than the player has any idea what to do with. And to cap it all, Zigzagoon makes a great HM slave, with access to Cut, Strength, and Rock Smash in a single Pokémon. This got so bad that FireRed and LeafGreen heavily nerfed the ability, which almost never happens within the same generation (in those games, it gives the player mostly Berries, which, though scarce in Kanto, are far less useful).
 * Emerald changed the scaling for Pickup too - it's far more useful than Fire Red and Leaf Green's Pickup, but still slightly less broken than Ruby and Sapphire's, as getting the better items require you to be at a higher level.
 * An easy way to screw with the difficulty curve in Pokémon Colosseum is to abuse a bug that allows you to use any Ball an infinite number of times. Because much of the challenge in the game comes from catching the Pokémon of competent Trainers instead of those in the wild, taking advantage of would-be scarce early Great Balls and midgame Ultra Balls allows for many battles to go much easier than they normally would, and the money saved by not buying Balls and selling spares can be used for many more Revives than would be normally expected. And then you get the Master Ball...
 * In the main game of Emerald, you can catch Rayquaza near the end of the game. Unlike in the rest of the series, the version legendary is at level 70 in this game, far above anything else in the main game, so if Rayquaza is used for the rest of the game, there will be no challenge at all.

Fourth Generation

 * The Sinnoh region is generally broken in half by a single Pokémon: Staraptor. The very first route allows you to catch wild Starly, which can swiftly become an extremely dangerous Pokémon with its access to a very early Wing Attack and Double Team by level, and when it evolves (which, again, happens extremely quickly), it gets Intimidate. The two-Pokémon team of a Staravia and a starter can wipe out most of the game until Staravia evolves, at which point the starter becomes obsoleted with the move Staraptor gains upon evolution: Close Combat. This move allows Staraptor to one-shot Rock and Steel types, the two types that had always resisted the otherwise insanely overpowered STAB Normal and Flying attacks, as well as stop Ice types who could normally take down a Flying type in one shot. Platinum then proceeded to make this even worse by giving the player the TM for Return right away. Guess who the most common candidate for that TM is?
 * Pair Staravia with Prinplup, and you can really do some damage. Prinplup learns Bubblebeam, which takes out most rock-type 'mons in one hit. Not to mention it learns other powerful moves like Fury Swipes, which can do a lot of damage if it hits 5 times.
 * Generally speaking, in the fourth generation, Dragon-types were heavily buffed; with the introduction of new Choice items, Salamence became completely unpredictable, especially when factoring in the new move Draco Meteor, a special Dragon-type move which basically one-shotted anything in the...claws of a fully evolved Dragon-type Pokémon. Outrage was also buffed, becoming to one of the deadliest attacks in the game in Generation IV. The extremely popular buffing move Dragon Dance, due to its Dragon typing, had wide distribution among Dragons. And to cap it all, there was Garchomp. With the advent of the physical-special split, Dragon Claw and Outrage went from being special moves to physical, letting Salamence, Dragonite and Garchomp run STAB Outrage off their far superior Attack stat. All of this resulted in a metagame of Dragons running rampant and Steel-types becoming prevalent mainly to counter the dragon menace. Eventually, Garchomp, Salamence, and Latias were all Kicked Upstairs into Ubers, resulting in Dragonite being the only real such threat left in standard.
 * To explain more about Garchomp, quite simply, it's easily one of the most powerful non-legendary Pokémon ever created. It possesses an excellent Attack, one of the best possible offensive typings in the game, very good Speed, and decent defenses for an offensive Pokémon.
 * The most popular item for Garchomp is the Yache Berry. It cuts the effectiveness of Ice-type attacks, Garchomp's only major weakness. This allowed it to get a Swords Dance off and practically guaranteed one or two KOs before Garchomp goes down. Which ties into the reason why Chompy got Kicked Upstairs into Ubers; in its heyday; it reduced practical diversity to the point where nearly every team that stood a chance was forced into something like this: Garchomp, Garchomp Counter x2, Counter-Garchomp-Counter x2, filler.
 * An even more hated version is Bright Powder-Chomp. Using Garchomp's Sandveil ability (opponent accuracy is cut to 80%) and adding an additional 10% for the item means that attacks hit him a maximum of 72% of the time in sandstorm, which by the way is painfully easy to set up (all you need is a Tyranitar). All you need to do is Substitute repeatedly until you dodge an attack, Swords Dance, and sweep. This is all made even easier because Garchomp can switch-in and force out most Pokemon because of how impossibly threatening it was. If you switch out while Chomp subs, gg.
 * Despite the fact that Generation 5 brought more ways to check Garchomp, he got banned. Again. Even with checks such as Balloon Heatran who could come in on any attack and KO as long as Garchomp wasn't hiding behind a Substitute with Hidden Power Ice, if Garchomp WAS hiding behind a Substitute, it didn't stand a chance. In fact, the combination of Substitute and Swords Dance in a sandstorm was a menace to anyone who couldn't break the substitute and take out Garchomp before it boosted too much or set up another substitute.
 * Mentioned in Platinum: one of the things Volkner can say when he visits your Villa is that all of his Pokémon are potential Game Breakers.

Fifth Generation

 * In the Pokémon Black and White main game, while the strategy of relying on one team member has been largely nerfed, one Pokémon still stands out: Archeops. Archen is available relatively early with minor backtracking, is extremely easy to nature reset for, and already has a physical Attack greater than that of Arcanine, and that's BEFORE it evolves. After gaining three levels, it learns the Acrobatics move. This move (which it gets STAB on) doubles in power if the user isn't holding an item, from 55 to 110, which with STAB is 165 - for perspective, a Hyper Beam has 150 power. When it evolves, its power grows to even more ridiculous extremes, now surpassing that of Pokémon like Salamence, and its Speed grows to match. The only downside to this creature throwing around nukes like breadcrumbs is its Defeatist ability, which halves its power if its HP falls under 50%...in a game where you can buy healing Lemonades extremely cheap from any vending machine...which are basically everywhere.
 * It gets even worse when it evolves, and you give it leftovers and Protect for one of its moves.
 * And then there's Axew. See above everything about Dragons in the fourth generation, realize none of that was nerfed, apply that to a Pokémon that gets Dragon Dance one level after you catch it and already comes with STAB Dragon Claw free of charge, and evolves after a mere six levels after that, with another evolution on the way, and you can see why it's being mentioned on this page.
 * Here's an In-Game Breaker that probably nobody saw coming. Say hello to Lilligant. Just another mediocre Grass-Type right? WRONG. Sleep Powder, STAB Giga Drain, and Quiver Dance (Boosts Both Special Stats AND Speed in a single turn). Using one with the Own Tempo ability in combination with the now 120 base power STAB Petal Dance (The 'Own Tempo' ability blocks confusion, including self-inflicted confusion.) and you have one of the most destructive sweepers in the game.
 * Also from the maingame is the Lucky Egg item. In previous games this was an extraordinarily rare steal from Chansey, but in this game it is simply given to you free of charge about halfway through. It greatly increases the experience of the mon holding it, allowing you to gain levels at ridiculous rates provided you kept going through the tedium of redistributing it every time you switched your active Pokémon - of course, it's totally worth it to outlevel the Elite Four without any extra Level Grinding on Victory Road unlike the previous gens, and turn the game between getting the Lucky Egg and the Elite Four into one giant Curb Stomp Battle.
 * A big one is the option for players to download both Mewtwo level 70 AND Arceus level 100 into Black and White from the Pokemon website. Have those two both in your team, and most of the in-game opponents don't stand a chance. Admittedly the second battle with the final four and the battle with Alder (Their 'mons are all in the 60s and 70s that go around) still require some potions on hand, but still, it's way easier than it'd normally be. Human opponents likely wouldn't be able to withstand them either, unless they were leveled up to the 70s or more.
 * And now you can get Reshiram or Zekram as well, depending on your version. The part where your mons randomly disobey you until you have enough badges probably helps to dampen the legendary rampage a bit, but still...
 * Audino has mediocre stats, a poor movepool and looks silly. However, they give massive amounts of experience, almost guaranteeing a level-up if something is at the exact same level as it. Plus, while Audinos only appear in rustling grass, it's not difficult to simply walk back and forth outside of the grass to force it to appear. Did we mention that Audinos appear on "every single place in the game that has grass?" Combine this with the above mentioned Lucky Egg, and you'll never have to worry about being underleveled again.

Pokemon Mystery Dungeon

 * The Pokémon Mystery Dungeon spinoffs aren't immune to this either. Most of the Game Breakers in the first two games (Red Rescue Team and Blue Rescue Team) were Nerfed in the later games (Explorers of Time/Darkness/Sky), however. A short list:
 * Due to a programming oversight (No Pokémon in the first games was given a gender except for the main character), moves that caused the Infatuation status (Attract and the ability Cute Charm, at that time) were absurdly powerful, basically being a nigh-effortless way to ensure that enemies almost never got a chance to attack you. Not to mention the Unfortunate Implications of making everybody fall in love with you...
 * Due to the special properties of the Pokémon Castform and its signature move Weather Ball, a single Castform could do enough damage to KO any non-boss Pokémon in a single hit at low-to-middle levels, and at high levels, could even do the same to any boss Pokémon that didn't resist Fire or Water. This was only minorly Nerfed in the Explorers games; Castform now has a 'size' of 4, meaning only one can be on a party and at the expense of another Pokémon, but most normal dungeons don't need more than the single Castform at one time anyway.
 * Upon maxing their IQ (the Pokémon Mystery Dungeon equivalent of 'Happiness', boosted by eating Gummi items), some Pokémon acquired the ability "Super Mobile", which allowed them to travel over water, lava, clouds, and even allowed them to bash through walls to make their own path with absolutely no penalty. In a Roguelike game, this naturally causes most of the difficulty to soar right out the window. In the Explorers games, this ability was severely restricted to a single legendary Pokémon, Palkia, whom you can only obtain after the game's storyline, making it more of a Bragging Rights Reward.
 * Speaking of Pokémon Mystery Dungeon... X-Eye Seeds snap boss battles right in two. The AI will never attack while under this effect, unlike during Confusion, and Crosseyed status probably lasts the longest of any adverse status effect short of stat drops. Eating an X-Eye Seed reveals that they cause the victim to hallucinate that everything looks like a Substitute.
 * Also, several IQ skills on the right IQ groups to boost HP, PP, and other stats could be further combined with Three-Star "Exclusive Items" that buffed a particular Pokémon each (generally giving them Absorption against a type they're usually weak against, or putting them in permanent Light Screen/Reflect status). Not only that, but the effects of those items are shared among all Pokémon belonging to the same evolutionary branch! So for instance, Pokémon like Gallade, Hitmonchan, Vileplume or Politoed could not only gain the buffs of their former evolutions, but also those of their counterpart(s), for a total of 4 buffs. And the Eevee family...
 * Want to top even this? Then bring along also the two-star equivalent of the Exclusive Item to get an even bigger stat boost, make your 'mon binge on stat-rising items like Life Seed and Iron, and keep in mind that some of the rarest Exclusive Items affect all the 'mons of the same Type. Pair it with a double-type, and...you know the drill.
 * Multi-Hit attacks (Bullet Seed, Fury Swipes/Attack, Pin Missile). Due to the damage calculation in the Mystery Dungeon games being much different than the mainstream titles, these move actually hit as hard as most other attacks per hit. The brokenness comes from the fact that the STAB bonus from the mainstream titles is also implemented in the Mystery Dungeon games, meaning with the right Pokémon (A Treecko with Bullet Seed and the Concentrator skill for instance), this can be quite lethal.
 * Speaking of Bullet Seed: because of how damage mechanics work, it can perform up to five ranged attacks, each of which deal a great deal of damage by themselves. And if you happen to KO the 'mon in front of you? It keeps attacking the ones behind it until you either run out of moves or targets.
 * If you think that's bad, try linking Screech with a multi-hitting move, like Meowth or Persian with Fury Swipes, and watch how fast you take your opponents down.
 * In the original game, Protect made you invincible to damage for one turn, and Sonicboom only did 20 points of damage regardless of the Pokémon's stats. In the Mystery Dungeon games however, Protect now stays in play for multiple turns, allowing for multiple attacks while the opponent is helpless, and Sonicboom is a ranged attack that hits for 55 points no matter what. Also, unlike the original games where most Pokémon could easily have 200+ health points at the end of the game, most Pokémon naturally won't even reach triple digits (100+ health points) at the later points of the game, so just imagine how devastating and frustrating 55 direct points of damage from a distance, (specifically off-screen) would be.
 * There was also Shedinja from the Pokémon Mystery Dungeon series, who unlike in the regular games where they were limited to 1 health point no matter what, were able to eat Sitrus Berries in order to increase its health to maximum. Couple that with the Wonder Guard ability, and the Super Mobile ability in the first game which is obtained by eating enough Gummies to reach maximum intelligence, to see how destructive one Pokémon could truly be.
 * Attacks that hit the entire room are usually game breakers, i.e. Earthquake. Who cares if you wipe out your teammates (Or, maybe not, considering the hit radius is ONLY an entire room and teammates in corridors are safe) if you can curbstomp an entire Monster House? Or, for even more mileage, you can link Earthquake with an ability like Protect. Wipe them out, then defend yourself! The worst part is, a single Pokémon can have a multi-hit ranged move, a defensive move, and a room-clearing move, and will likely not find much use for any of their moves because that Pokémon will likely be stat-grinded enough from feeding it Gummis that it's generic attack one-hit KOs anything that's not a boss.
 * Pfft please, if you want a nasty one try Heat Wave, which hits all the enemies in the room AND leaves your allies unharmed. Same with Silver Wind, or any attack that hits the room all at once. On top of that it can be linked, and Charizard has it from a VERY LOW level, making dungeons that force you back to level one to be a snap with a Charizard on your team.
 * Zapdos can be considered one since it learns Agility, Charge and Discharge. Try linking all three of those moves in that order and see what happens to a monster house.
 * If you're talking about room affecting moves, specific mention has to go to Agility which raises all Pokémon on the same team's speed greatly, and moves like Silver Wind which hit the entire room, and can power up all of the stats of the one who uses it.
 * You can't forget the abilities Chlorophyll and Swift Swim, which in the main games boosted speed under Sunlight and Rain (respectively). However, since speed doesn't work in the same way in these games as it does in the other games, they had to figure out some other way to have the ability manifest itself. Of course, this comes in the form of having your Pokémon attack twice in the same turn for the PP cost of ONE attack. Now combine this with either Groudon or Kyogre, an already broken move like Heat Wave, and the fact that Fire/Water moves get a boost in that weather...

Trading Card Game

 * The Game Boy Color version of the Pokémon Trading Card Game, faithful to the original game, had hundreds of cards that relied on a coin flip. For example, the Poké Ball card allows a player to search their deck for any Pokémon and put it into their hand, but only if a coin flip comes up heads. This was not in itself unbalanced, but the problem came when the game's coin flipping system was not randomized. A player with a good sense of timing could earn a favorable result on every coin flip. This made cards like Vileplume and Kangaskhan able to destroy an opponent in just a few turns.
 * On the subject of the Game Boy Color version, Imakuni? was a Game Breaker. He was weaker than all the AI characters, but if you defeated him (which was quite often), he gives you an unheard-of four booster packs. This makes racking up cards rather easy.
 * There's also Pokémon like Hitmonlee who could attack your lead Pokémon with a powerful move, or your benched Pokémon for 30 points of direct damage, easily defeating first form Pokémon with really low health in one or two turns, while it had enough health to last for a while if you didn't have a powerful psychic Pokémon to counter it.
 * Similar to the above example the "Haymaker" cards which are basic Pokémon cards with HP comparable to most evolution cards and low energy costs; Scyther, Hitmonchan and Electabuzz can give you a massive advantage at the beginning of a match and then there's what happens if you have four in a deck.
 * The Pokémon Trading Card Game underwent Sequel Escalation for each generation that was released, plus another for HeartGold and SoulSilver. It's reached the point where the old Haymaker deck is easily overpowered. This is due to an increased emphasis on evolution in that evolved Pokémon get lower Energy costs for greater effects, more Pokémon capable of hitting the Bench, vastly improved Trainer cards (since then split into Trainers, Supporters, and Stadiums) that can easily search for cards of your choice from the deck or discard pile, and a trend away from Energy being the requirement for attacks, instead leaning towards other effects on the field. Together, this has resulted in a frenzy pace, most tournament decks refined to be fully set up in 1 turn, or 2 at most. For instance, Gyarados has an attack that does 30 damage for each Magikarp in the discard pile. A popular deck is designed to use Rare Candy to evolve a Magikarp on the first turn (bypassing a rule prohibiting this), find the 3 remaining Magikarps and discard them, attach an Expert Belt (which boosts attack power by 20), and use this move for 110 damage. Also, this attack requires no Energy at all. Compared to decks like these, the Haymaker is but a light jab.
 * The Team Rocket booster packs, full stop. These had such Pokemon as Rocket Blastoise who could use its "Rocket Tackle" attack for 40 damage, and flip a coin which if it was called right, negated any damage from the opponent in the next turn including status effects, all for reducing its health by 10 HP, Rocket Charizard who had an attack called "Continuous Fireball", which for one fire energy it could flip a coin until it got tails, and the attack did 50 points of damage to the opponent for each heads it got, and the best part is that most of these overpowered cards were common cards. The rare cards were even worse like Rocket Dragonite who had a power that allowed you to put two Pokemon on your bench at once while it was in battle, and a Trainer Card called "Here Comes Team Rocket" which made both players play the game with their prizes face up, and eliminating the random possibility of picking a weak prize after a victory while thinking of a proper way to use your prizes in any order you want, while keeping an eye on your opponents possible prizes at the same time.

General Competitive Multiplayer

 * In official tournaments for the Pokémon games, the use of insanely-powerful Pokémon (which are dubbed "Ubers") is almost invariably banned. Most of the Ubers are intentionally overpowered (most of the unique legendary Pokémon fall under this category, since they serve as an ultimate challenge for those going for 100% Completion), but a few aren't. Some of these Pokémon (namely Wobbuffet) have very few learnable moves, but a combination of a special ability and high endurance can guarantee that at least one of its opponents will go down before it does.
 * OU is considered the standard tier, anything below it being questionable for use in tourney play. Only very specific OU Pokémon draw ire, those being the most effective ones.
 * Ubers also see use in the Pokémon Battle Revolution random Wi-Fi, where Nintendo has not banned them, oddly enough.
 * That's because tiers are entirely decided by the fans. That they haven't banned Legendary Pokémon (and Wobbuffet) from Wi-Fi play like they have from the Battle Frontiers in the later games, however...
 * Even among the Purposefully Overpowered Pokémon, in Uber Tier of competitive play, there's some Pokémon who stand out too much and need a mention. Groudon and Kyogre are exceptional. Not only do they have an excellent stat spread and very broad movepools, they have an ability that change the weather upon switching in, which can easily turn the tide of battle.
 * Kyogre gets special mention because unlike Groudon who's a Ground-type Pokémon with an ability that raises Fire-type moves, Kyogre's a Water-type Pokémon that has an ability that raises water type moves, and boosting its Water-type moves along with STAB! Oh, yes, and it can learn Thunder! Combine that with the fact that its Drizzle ability is a permanent Rain Dance on the field (at least until someone else changes the weather) and you have the move Thunder hitting 100%, along with possible paralysis and Ice Beam for any dragons that try to resist its attacks. Consider that its Special Attack are on the same rank as Mewtwo with considerably better bulk, give it a Choice Specs to boost its Special attacks further, or Choice Scarf to raise its speed to the point where only a few Pokémon without Choice Scarf itself could exceed it, to see how devastating it is in battle. Simply put, Kyogre is the Stealth Rock of Ubers: you MUST have a counter for it if you want to win. This Pokémon IS Game Breaker incarnate in its own tier. So much that you might see Com Mons such as Quagsire, Lanturn, Shedinja, and recently Gastrodon in Ubers just to beat Kyogre.
 * Groudon is no joke either. 150 base attack, and 140 base defense paired with solid 100 base HP makes it a very sturdy tank that even Rayquaza's outrage can't break easily. He has a crazy movepool including Thunder Wave, Stealth Rock, Rock Polish and Swords Dance. Oh and he's a ground type meaning he gets STAB Earthquake which is awesome and is immune to thunder wave. In terms of power, if you, by some case, let Groudon set up more than 1 boost, you're going to face probably the most unstoppable physical sweeper in the whole game.
 * While in lower tiers it suffers from no good abuser(as of gen 5, only 2 abusers are really great and the other abusers, while good, are no match for rain abusers), in uber tier sun (that is summoned by Groudon) has many great abusers such as Ho-oh and recently Reshiram in gen 5. Kyogre might be better on a single comparison but in terms of a supporting role, Groudon outclasses Kyogre with both its ability and movepool.
 * However, the most potentially devastating of Kyogre's moves is Water Spout. Water Spout has a very high base power, rivaling the Awesome but Impractical Hyper Beam, and it doesn't need a charge up turn and therefore is practical. The downside is that it becomes considerably weaker as Kyogre's HP goes down. However, with the aforementioned Choice Scarf, it could outspeed a good portion of faster Pokémon. AND if you try to use Choice Specs to it, this move is able to beat Blissey in TWO hits WITH SPECIAL ATTACK. A feat that no other Pokémon in the game can do without a massive amount of buffing. In fact, only Latias with Soul Dew is able to switch in safely on Choice Specs Water Spout from Kyogre.
 * Arceus also deserves a mention. A 120 base stat spread in everything, a movepool only rivaled by Mew and Smeargle and the ability to change its type by holding elemental plates makes it a very versatile and dangerous Pokémon that is able to duplicate almost every Pokémon in the game and do the same roles with the same level of efficiency all in one package. It effectively rivals Kyogre in term of Brokeness.
 * To show how insane Arceus is statistically, see Kyogre and Groudon (the two most common Pokémon in ubers that are overall the best Pokémon) and their stats. Kyogre and Groudon only win in attack and their respective defensive side(physical and special respectively). But on the attacking side, Arceus has 120 speed on his side, significantly faster than both since that means even with very little EVs, Arceus is faster than either with the maximum speed they can reach. It also means the resident Stone Wall Lugia is slower than Arceus. On the defensive side, despite the differences, Arceus is only slightly less bulky on the weaker defensive stat. So little that it's no matter at all. Oh, and did we mention that by forgoing some hold item it can change its type AND getting boosted STAB at the same time? Let's not start talking about its notable moves and It Got Worse.
 * Mewtwo, the original legendary Game Breaker. Insane movepool, high stats, and unlike Deoxys is actually bulky in addition to being the 4th fastest Pokémon commonly used in the uber metagame. And as if that's not good enough, Generation V gave it Psystrike, a signature move that has good base power and hits physical defense with special attack. Yeah he is so awesome that he is now THE one and only Pokémon in the metagame that has an excuse to run its previously unseen Psychic STAB move without any drawback.
 * At first, Psystrike is still not very effective against other Psychics and Steels and useless against Dark-types, which means half of the Uber tier is still resistant to Mewtwo's STAB. Until you realize how Psystrike makes a really big difference. First off, it doesn't need to sacrifice itself to beat Blissey. Second, it might be bad, but considering the commonly used Pokémon in ubers is not psychic or can't take Psystrike is a big factor too. Mewtwo also has Aura Sphere, Shadow Ball, and Fire Blast to cover the coverage to hit everything you need to hit.
 * Finally factoring Stealth Rock, it can hit everything he previously needs specific move to hit with enough damage especially with Calm Mind up. Psystrike gives him an excuse to run STAB, and ability to beat Kyogre and Blissey more reliably with his Calm Mind Set.
 * Palkia. Extremely powerful STABs, capable of running a mixed set, wreaks havoc if used with Kyogre. It can even sort of counter Kyogre, with a quad resistance to Water-type attacks. Blissey? Palkia used Aqua Tail. Groudon's Drought? He won't live for much more with his only average Special Defense. It's just as capable in Generation V considering Latios and Latias currently can't get Soul Dew.
 * Dialga. It's for a reason why he almost always a top 5. Awesome typing that resists stealth rock and is immune to Toxic and Toxic Spikes, awesome movepool, and it even learns Stealth Rock and receives a very great stats spread offensively and defensively. This thing is basically a Droughtless Groudon with Dragon typing.
 * Generation V's metagame has not yet crystallized but one playstyle on online simulators provoked quite a bit of outrage; Rain teams. See, thanks to the Dream World being able to unlock Pokémon with unique hidden abilities, Politoed now has Kyogre's Drizzle ability, summoning permanent rain storms. Combined with the speed-doubling ability Swift Swim and Water's fantastic defense and neutral coverage, the metagame was completely annihilated by a blitz of obscenely fast, strong, and bulky water Pokémon, with previously overused Kingdra and strictly underused threats Kabutops and Ludicolo being considered Uber-level fighters. Add to that Manaphy, who can maximize his special attack with two turns of setups and is immune to status in the rain (letting him instantly heal with Rest) and it's no surprise that Rain was completely dominant in the Generation V metagame until Smogon declared it illegal to utilize Drizzle and Swift Swim together.
 * What makes rain more devastating than sunlight isn't as is said in Groudon's niche over Kyogre is the lack of a great sunlight abuser. In standard, only some sunlight abusers are good and Venusaur pretty much shows the face of sunlight abusers among Chlorophyll users (high Speed, great coverage, bulky, insane movepool). While not exactly bad, Rain however, has Kingdra which, when combined with choice specs, can spam Hydro Pump and Draco Meteor, essentially his STAB attack all day long which only resisted by two Pokémon, one of which is used on almost every team but can't take repeated hits and the other is pretty much unseen nowadays leaving only Blissey as the reliable one, and Kingdra can also (although inferior) use Dragon Dance. Combined with Ludicolo and Kabutops, during the days of Drizzle, they are called the Broken Trio(KingColoTops). The might of the Broken Trio is proven by surpassing even Manaphy's usage during the short time before Manaphy's ban.
 * Also note, sunlight can only have one of high Speed or boosted Attack. Rain can have both. This plays a big factor in making rain broken.
 * Even more, in spamming terms, water is better than fire. The Water-type is resisted by grass and other Water-types. The most sturdy grass, even when common in the metagame, can't withstand repeated hits and don't have reliable recovery. Other Water-types succumb to Ludicolo and Thunder (which never misses in rain). Fire, while their main water resistor is crippled by sunlight, their second resistors are....Tyranitar and Garchomp.
 * And in abusing terms, rain has more abilities it provides users, too, and has great abusers without swift swim. Thundurus and Tornadus are examples of how insane the abusers of rain are compared to sunlight. The first one basically guarantees crippling two Pokémon with a mighty attack and Priority Thunder Wave. The second one can just spam his massively powerful move with great coverage. When it's nearly fainted, however, it can just return the Rain Team to its old glory days of Swift Swim with EVERY Pokémon in the team for four turns.
 * Worth noting even with THAT ban, rain is the most common team in a Smogon match. So much that some think rain is thoroughly Broken.
 * Another Generation V Game Breaker banned by Smogon is the Moody ability, which causes one stat to be sharply raised (essentially a free Acupressure boost) while another drops one stage every turn. Despite appearing on otherwise overlooked Pokémon such as Bibarel, a few turns of stalling can result in an unstoppable, Nigh Invulnerable Pokémon capable of demolishing an entire opposing team, especially considering one of the stats that can be boosted is Evasion.
 * Worse yet, one of the Pokémon who got Moody was Smeargle. Anyone who's heard of Smeargle knows its defining characteristic is its movepool, which contains every move in the game barring Chatter and Struggle. Imagine all the things mentioned above, apply them to that, and you can see why it's on here.
 * Some calculations were done involving a Smeargle with stored power. After stalling for a while, Smeargle at +6 Special Attack, and +6 in most stats, could 2HKO Blissey with Stored Power. And if something immune to Stored Power came along, then it could just as easily Baton Pass those boosts to something else. The only way to get around it was to force the Moody Pokémon out somehow or use Unaware, whose main users are also fairly weak statistically.
 * And as a bonus, the most well known users of Unaware, Bidoof and Bibarel, also get the Moody ability.
 * A newcomer to the Generation V uber list is Blaziken. Its new Dream World ability of Speed Boost raises Blaziken's normally mediocre speed by one step every turn (and it can use Protect to guarantee that first crucial turn), and the retooled Hi Jump Kick grants Blaziken a devastating STAB move that doesn't lower its stats. Add Stone Edge or Shadow Claw for coverage, and there are few things that can switch into Blaziken without promptly being obliterated.
 * Its biggest power is the fact that you need to deal with it FAST. Even with that it has high chance to cripple a team with its massively powerful STAB attack.
 * Excadrill. It has one of the highest Attack stats in the game, and one of the best STAB types, though it appears to be balanced out by its mediocre Speed. However, its ability, Sand Rush, doubles speed in Sandstorm. Yes, DOUBLE SPEED. In fact, it reaches speeds so high almost nothing can outrun it, and it hits like s truck too. Oh, and the Pokemon with instant Sandstorm setup, Tyranitar, is also quite the Game Breaker itself and is seen often, so Excadrill has plenty of chances to go crazy. Also, it can also learn Swords Dance; let it get one off, and you're headed for a Total Party Kill. Priority is pretty much the only thing that can stop it. It should come as no surprise that it got banned.