Ryu and Ken



A common trope seen in Fighting Games, where two characters are given equal or similar abilities/appearances, and often wind up as being the main characters for the series. In some cases, the two characters may have an implicit rivalry, if not outright hatred for one another. They usually are colour coded to represent Red Oni, Blue Oni scheme.

If both characters are playable, both may be Jack of All Stats. Even if they have the same movesets, they can't be considered Ditto Fighters, since they only emulate one other character.

In many cases, a game's Ryu and Ken are Shotoclones; however, this is not always the case, and not every Shotoclone is a Ryu And Ken.

The Ken might later be subject to Divergent Character Evolution to differentiate him from the Ryu.

Some games will even expand the concept further with other character types: 


 * The Sakura (no, not that Sakura, or that Sakura, or that Sakura, or that Sakura, or that Sakura, or that Sakura, definitely not that Sakura, and not to be confused with the Sakura Girl trope) is also similar to Ryu and Ken, but is overall smaller, weaker, and usually has less effective attacks. They may add new twists to the attacks to compensate, however, such as being faster. They will often be female (typically presented as the smaller but faster female counterpart to the male Ryu and Ken), though this is not a universal rule.
 * The Akuma (no, not that Akuma) is basically the same character type upgraded to a Game Breaker. He has the same moves, but he will move faster, hit harder, and more often than not has much higher priority for his moves plus nasty little tricks and variations added to them. They will usually be the Final Boss or Bonus Boss of the game before they are playable, and will be hard as hell to beat.
 * The Dan Hibiki is the Joke Character or Lethal Joke Character version. Expect weak yet hilarious attacks.

Not to be confused with Ryu and Ken from Fist of the North Star, whose relationship is better defined by The Mentor.

Anime and Manga

 * Gundam also is this Trope like Loran and Gym having the Moonlight Butterfly Amuro and Char having the Psyco Frame and Funnels  Along with Domon and Master Asia having the Same Fighting Skills
 * Code Geass has Kallen and Suzaku. Their mechs look similar,
 * Mazinger Z and Great Mazinger could actualy be one of the earliest example. Both have exact same kind of weapon, the difference come with Mazinger Z having more ranged based and have less variety of weapons and Great Mazinger has more weapon variety and more melee based weapon than Mazinger Z.
 * Mazinger Z's long range weapon is more developed than Great Mazinger, such as the corrosive Rust Tornado, posession of Koshiryoku Beam and Reitou Beam and its detachable wing also function as Throwing Weapon. Later on its upgrade focus on enchancing this by giving the Rocket Punch a power boost or spinning it before launching the attack.
 * Great Mazinger's Great Typhoon lacks the corrosive property of Mazinger Z, and lacks Koshiryoku Beam. In return, it has several melee oriented weapons, and most of them are physical such as a pair of Mazinger Sword, Great Boomerang, and Knee spikes and Curved Blade on front of its leg. To make up for this, Great Mazinger also have Thunder Break for long range weapon and his Finishing Move, and Tetsuya makes it up by using his weapon creatively, such as throwing his swords or using Breast Burn to cover his body. His upgrades gives him better capability on both side, since Great Booster function as long range weapon, and gives increase on speed.
 * Both Grendizer and Mazinkaiser serves as the Akuma, both combines the aspect of two machines and put them on one mecha. Grendizer is more simmilar to Great, while Mazinkaiser is more simmilar to Z.
 * Ironically, in Super Robot Wars, Z become more of a mellee based unit while Great become a better sniper unit thanks to his multitude of long range weapons, while Grendizer become Jack of All Trades and Mazinkaiser become Lightning Bruiser of the group.
 * Dragon Ball: Goku and Vegeta. Both are full blood Saiyans with similar fighting styles and equivalent attacks, (Kamehameha versus Galik Gun) conflicting personalities and a strong but respectful rivalry, and they're always close in power level, constantly competing with each other. Their similarities even let them fuse together at one point. Their sons, Goten and Trunks, also show even more shades of this, complete with the fusion part and inheriting their fathers' moves.
 * Ranma ½: Ranma and Ryoga - Eternal rivals, evenly matched, and even fit the personalities. Ryoga is a stoic chivalrous wanderer like Ryu, whereas Ranma is an arrogant, happy-go-lucky, egomaniac like Ken. The difference being that Ryoga is more powerful, durable, and straightforward, whereas Ranma is swifter, more acrobatic and strategical.
 * While many characters see Ranma as their rival, Ryoga is the only one Ranma considers such, they also share an attack (which is their strongest), Ryoga is the strongest character in the series besides Ranma, Happosai and the ocasional Big Bad, they learned their respective second strongest attack from the same teacher (Shampoo's grandmother), Ryoga has beaten Ranma more times than any other character (including Haposai who's supossedly the strongest charater in the series) and he's the only one Ranma trusts enough to willingly fight alongside with.
 * Zatch Bell features this for two of the strongest characters in the series; the eponymous Shock and Awe-based character and his Evil Twin, and Gravity Master Brago and Zofis, his first main foe. The latter's spells are based on explosions.
 * Tenchi Universe has Ken-ohki and Ryo-ohki.

Comic Books

 * Superman and Captain Marvel have shades of this when they appear together. Since the latter was originally a Captain Ersatz of the former, it's not surprising.
 * Supergirl typically acts as the Sakura to Superman when the two appear together.
 * X-Men: Banshee and his daughter Siryn; both are quite adept at sonic attacks. Siryn's twist is that she also has a Compelling Voice.
 * X-23 is the Sakura to Wolverine in both the comics and Marvel vs. Capcom 3.
 * Spider-Man and Scarlet Spider could count. Justified in that Scarlet Spider is a clone of Spider-Man. Kaine would be the 'Akuma' as he has their powers dialed Up to Eleven. Spider-Girl(Mayday) would arguably be the 'Sakura'

Live-Action TV

 * Peter and Sylar on Heroes.
 * Kendra in Buffy the Vampire Slayer is another slayer roughly Buffy's height, age, and weight with moves similar to Buffy's.
 * Later on, Buffy and Faith, Faith getting a Faith Heel Turn.
 * Several characters seem to go through this. Spike and Angel are initially presented as virtual mirrors of one another, but by the end of the series their fighting styles are presented in deliberate contrast.
 * Only if you ignore the fact that Angel has about 50 lbs on Spike and yeah he is also 5 inches taller.

Professional Wrestling

 * The Undertaker and Kane. They use the same moves, are Kayfabe brothers of similar size and general appearance and, at various times, have been the two top guys in the WWF/E - most especially when Kane first debuted. They also have fairly similar movesets; both being fond of using the chokeslam and tombstone.
 * Matt and Jeff Hardy are another pair in WWE. Jeff has more daredevil high-flying moves, while Matt is the more solid wrestler, but on the whole, their styles are extremely similar, and they have an on-again, off-again case of Sibling Rivalry writ-large. Jeff even uses Matt's Finishing Move, the Twist of Fate, as one of his own signature moves.
 * Hulk Hogan and The Ultimate Warrior—both tall, tanned, musclebound, insanely-popular-and-powerful brawler/power wrestlers hailing from the southwestern United States (OK, Warrior's from Parts Unknown, but the man behind the gimmick's from Arizona) with a bodyslam-heavy arsenal and the ability to hulk up in '80s/early-'90s WWF. Of course, the fans just had to see them battle each other at Wrestlemania VI.
 * And considering the two involved, the resulting match was more awesome than it had any right to be.
 * Could Macho Man Randy Savage be a Sakura? Similar style, slightly different moves but same general idea?
 * Brock Lesnar and Goldberg—both were big, fast and strong Showy Invincible Heroes of their respective brands during the Brand Extension era. The two finally met at Wrestlemania XX, but unfortunately, unlike Hogan and Warrior above, the match was an Epic Fail.
 * Booker T and The Rock. Somewhat justified due to them being the Alternate Company Equivalent of each other.

Fighting Games

 * The ur-examples are the identical fighters from Karate Champ. Completely identical fighting styles, and they even wore a white and red gi.
 * The trope codifiers and trope namers, obviously, are Ryu and Ken from Capcom's Street Fighter franchise, having appeared in every game in the series to date. At first, they started off as clones of one another, having the exact same movesets and being merely head-swaps of one another (because the original Street Fighter had no scope for mirror matches, so they needed two identical characters for two-player competition play). During the Street Fighter II games, their stats, moves, and strategies began to differentiate, albeit little by little each new iteration, but by the time the Street Fighter Alpha series started they had distinct backstories and extremely similar, but not identical, abilities. Naturally, the series also includes the Sakura, Akuma, and Dan-types as well (Unsurprisingly, the characters with those names).
 * Though Sakura and Karin look like they would be Ryu and Ken reincarnated as teenage girls, Karin has an entirely different fighting style from her rival.
 * Yun and Yang originally had the same move set and even shared the same character select slot in New Generation, but Yang eventually learned his own techniques from 2nd Impact and onward. Urien and Gill are similar, but Urien is a charge-type character and not as brokenly overpowered.
 * Akuma and Gouken in Street Fighter IV. They're actually brothers.
 * Zangief got Darun from Street Fighter EX. Haggar could count as well, but they have never been fighters in the same game so far (although Haggar did get his own unique Special Moves in Ring of Destruction to set him apart from Zangief). Ryu and Ken also have Allen and Kairi from EX
 * Cammy has Juni and Juli, Bison's bodyguards, in Street Fighter Alpha 3.
 * Charlie was originally brought in as a stand-in for Guile during the Street Fighter Alpha series, but plays this trope straight when Guile was put back in the roster for the console versions of Street Fighter Alpha 3, (and Marvel vs. Capcom 2) where they both have identical special moves but different Super Combos. Chronologically speaking, the Alpha series is set before Street Fighter II and Charlie was the one who taught Guile all of his special moves according to his back-story.
 * SNK's Alternate Company Equivalent, The King of Fighters, has Kyo Kusanagi and Iori Yagami. Their movesets were originally somewhat similar (justified in that their ancestors created their respective fightig styles together), with several shared moves; Currently, however, they only have one move in common. Kyo's flames are red, and Iori's are purple due to the Curse of the Blood Riot. Iori is much more sadistic, although not an outright villain (even though he likes to break into evil laughter from time to time). Kyo is also the Ryu to Benimaru Nikado's Ken, and the Ken to his father Saisyu's Ryu.
 * Non-protagonist examples from the same series are Ralf and Clark, and Mature and Vice. Ralf and Clark, the Palette Swap heroes of Ikari Warriors, started out as head swaps with differing intros, winposes, throws, knockdown moves, effects on one of their shared attacks, and desperation moves. Nowadays, it's hard to imagine these two were ever that similar. Mature and Vice, on the other hand, shared outfits, normal moves, throws, and one special move (a command throw) in their 96 debut. Like the Ikari Warriors, their 98 return had them undergo Divergent Character Evolution such that all that remained the same were their weak punches and throws.
 * They are all predated, of course, by Ryo Sakazaki and Robert Garcia in the Art of Fighting series.
 * Kim's sons, Kim Jae Hoon and Kim Dong Hwan, however, play very similarly to each other and to their father in Garou Mark of the Wolves.
 * Shingo may not have flames, but his fighting style is similar enough to be the Sakura/Dan to Kyo and Iori, though his new twists to the moves make him more than just a carbon copy of Kyo. The fact that his moves are fairly weak in comparison to other characters means he skews more towards Dan, though he tends to be much more viable.
 * Predating even Art of Fightings Ryo and Robert are the three-man Ryu and Ken' And Ren? Kyu? team of Terry, Andy and Joe in the original Fatal Fury only. They each had a fireball, a dashing attack, and a flying attack with the potential to hit multiple times, with only their fourth special and the ranges on their normal attacks being functionally different (and even that fourth move was incredibly similar for Terry and Andy). Fatal Fury 2 added more and more varied normal attacks, tweaked the properties of their specials to help differentiate them, and gave them each a completely unique Desperation Move. Nowadays, their gameplay styles are nothing alike.
 * The King of Fighters XIII brings back an older, almost-forgotten example: friendly rivals Joe Higashi and Hwa Jai (from the first Fatal Fury). They share many a move, but there is a difference functionality-wise.
 * Hanzo and Fuuma from World Heroes, a Fighting Game with characters loosely based on historical figures. Japanese legend depicts Fuuma Kotaro and Hattori Hanzo as lifelong enemies, until the former ultimately killed the latter (though history actually records Hanzo dying of natural causes).
 * Urs and Marco Van De Land from Battle Fantasia, who also happen to be brothers. It's a weird case as 9-year-old Marco is the Ryu to 17-year-old Urs' Ken. And they manage to do this and come off as amazingly different at the same time, partly because of Urs' Impossibly Cool Weapon.
 * Another example from the same game is Olivia and Odile, who look similar, have similar weapons, and it turns out that.
 * The Mishima family (Heihachi, Kazuya, Jin) in the Tekken series.
 * Nina and Anna Williams.
 * Yoshimitsu and Kunimitsu.
 * Roger and Alex.
 * Eddy Gordo and both Tiger Jackson (in 3) and Christie (4 and onwards)
 * Kuma and Panda.
 * Baek and Hwoarang, atleast since 5.
 * Armor King and King,
 * Jack and P.Jack.
 * Marshall Law/Forest Law and Mokujin/Combot would count too, albeit they were never together in one game.
 * Eiji Shinjo and Kayin Amoh from Battle Arena Toshinden. Eiji's lost brother Sho qualifies as an Akuma—he has all of both Kayin and Eiji's moves, but he hits harder, and he shoots two fireballs when using Rekku Zan.
 * Sub-Zero and Scorpion from Mortal Kombat are about the closest thing the franchise has to a Ryu and Ken. They share the same Palette Swap in the original game, and they are quite bitter rivals in canon (Scorpion being the Red Oni and Sub-Zero being literally Blue), but their movesets are quite different, with Sub-Zero favoring ice attacks and Scorpion favoring spears, teleporting and fire.
 * Frost is closer to a Sakura for Sub-Zero, due to her being much more of a Fragile Speedster with much quicker but weaker attacks and special moves.
 * Kano and Jarek, although this is another case of a Suspiciously Similar Substitute meant to replace the former; they weren't playable in the same game until Armageddon.
 * Superman and Captain Marvel in Mortal Kombat vs. DC Universe play this. A stranger version is Lex Luthor and Sektor, who don't appear in the same game, but Luthor plays similarly to Sektor, even blatantly using similar special moves.
 * In Tatsunoko vs. Capcom, Ryu and Ken, except this time Ken is Ken the Eagle from Science Ninja Team Gatchaman.
 * With the addition of Joe the Condor in the Ultimate All Stars, along with Jun acting as the Sakura, the three Gatchamen play this trope straight among themselves.
 * Likewise with Tekkaman and Tekkaman Blade in Ultimate All Stars: The Tekkamen have many shared/similar techniques, but their executions are noticeably distinct. Tekkaman (the Ryu) is a Mighty Glacier (and might have the highest damage output in the game outside of the Giant characters), while Blade (the Ken) trades in some power for a good deal of speed, possibly making him just shy of being a Lightning Bruiser.
 * In Super Smash Bros.. Melee, in addition to standard secret characters, Dr. Mario, Ganondorf, Falco Lombardi, Young Link, Pichu and Roy are Kens to the Ryus of the character they are adjacent to (respectively, Mario, Captain Falcon, Fox McCloud, Link, Pikachu, and Marth).
 * Luigi is also largely a Ken of Mario's Ryu (or a Sakura to his brother if you toss in Dr. Mario), though there are some differences in their move sets (see below).
 * In the sequel, Super Smash Bros.. Brawl, more differences were introduced between Fox and Falco (Falco, for instance, can kick his Reflector shield at enemies as an attack), and a third Ken, Wolf O'Donnell was introduced, though he has even more move differences (in fact, none of his A moves are similiar to the other two space animals), is harder to control, and is more of a Mighty Glacier. The rest of the Kens were also changed to be different or removed.
 * Link and Toon Link. Ganondorf and Captain Falcon, everyone else is more notably different but no one is similar as the characters were in Melee.
 * God Hand, a throwback to old-school Fighting Games, nods to it with Gene and Azel. There's also several nods to the actual Ryu, including a karate outfit as an alternate costume and a Shoryuken as one of Gene's juggle moves. Capcom owned Clover, who made God Hand.
 * Soul Calibur III and IV seem to be taking this route with Siegfried and Nightmare. Only fair since they literally started out the same character.
 * The Alexandra sisters (Sophitia and Cassandra) have developed along these lines as well since the latter showed up in SCII (Though the latter was originally intended as a Suspiciously Similar Substitute until popular demand brought back the former for the console version of SCII and subsequent sequels).
 * Hwang and Mitsurugi started out like this.
 * Rock and Astaroth.
 * Raphael and Amy.
 * Kilik and Seong-Mina also shared a lot of moves in Soul Calibur in spite of their different weapons, but have differentiated more and more with each subsequent sequel. Seong-Mina's moves are straightforward and have changed the least, while Kilik now focuses on range and punishing opponents' mistakes.
 * Galford and Hanzo of Samurai Shodown. Originally being little more than palette/head swaps of one another, they eventually became more and more different with the addition of Hanzo's fire-based specials and Galford's ability to set his dog Poppy against opponents.
 * We also have Nakoruru and Rimururu. In the third and fourth game, the latter was a headswap of the former. They were quickly given different outfits in the later games. Nakoruru fights with a bird, Rimururu fights with a floating Nature Spirit crystal of ice.
 * Some of the Shura (Slash) and Rasetsu (Bust) mode pairs are like this in III and IV, while others are way different.
 * In the Naruto Clash of Ninja series, Iruka and Mizuki are this (in Mizuki's first appearance, the two shared character slots). Also, Kisame and Zabuza, both Swordsmen of the Mist, have similar movesets (more obvious in the Japanese games where they're both playable; Zabuza does not appear in the internationally-released Clash of Ninja Revolution games, while Kisame does).
 * Hinata and Neji have similar movelists, but many of Hinata's moves are original to the games (for example, instead of using Eight Trigrams 64 Palms, she repeatedly attacks an opponent with Gentle Fist palm strikes, then finishes with a burst of chakra), due to limited information on her fighting style. In the Ultimate Ninja series, Hanabi (Hinata's younger sister) follows a similar principle.
 * The game-exclusive characters in Revolution 2 count. Komachi is similar to Haku and Kagura is like Kimimaro. Towa and Bando, this troper is unsure of.
 * Biff Slamkovich and Gunloc in the Saturday Night Slam Masters series. Like Ryu and Ken, they have similar but not identical moves; The real differences come out in their grapples.
 * Arcana Heart features Heart and Saki, two friends with slightly different outfits who share a few normal attacks and both feature a dash attack, an anti-air attack, and a mid-air stomp attack. However, Heart's attacks are punch-based and use quarter-circle type inputs, while Saki's are kick-based and use charge motions.
 * In Ehrgeiz, the Final Fantasy VII characters are generally clones of other characters and have very similar movesets. Yuffie matches up with Sasuke, Vincent with Godhand, and (to some extent) Sephiroth with Cloud.
 * Secret Character Zack is very much a Ken to Cloud's Ryu, sharing a similiar move set.
 * Billy and Jimmy Lee naturally filled this role in the Neo Geo Double Dragon Fighting Game, as well as in Double Dragon V for the SNES and Genesis.
 * Darkstalkers has Morrigan the succubus and Demitri the vampire. They both have the standard "fireball" and "dragon punch"-style moves. Dmitri's moves are slower, and his uppercut flies straight up.
 * Lilith is the Sakura, having weaker specials than Morrigan, but a more diverse moveset.
 * Another set would be Bishamon and Oboro Bishamon in 'Vampire Savior''.
 * Sol Badguy and Ky Kiske from Guilty Gear. Unusual in that Sol (the main character) plays closer to Ken, while Ky (who is The Rival) plays like Ryu.
 * Castlevania Judgment has an interesting case with Simon and Trever. Both Belmonts use the Vampire Killer whip and have several similar moves (including at least one identical special), but Simon specilizes in quick, wide sweeps, while Trevor mixes it up with several jabs and slower, more powerful attacks.
 * Melty Blood has a handful of characters with a Doppelganger equivalent that serve as a Mirror Match, and so have some very similar movesets, natch.
 * Variable Geo has Yuka Takeuchi and Chiho Masuda as its primary set; later games would introduce Tamao Mitsurugi, who was a hybrid Ken/Sakura-type in her initial appearance, due to being the main character of that game; but returned for the next as more of a hybrid Sakura/Dan-type due to Divergent Character Evolution.
 * In the SNES version of Teenage Mutant Ninja Turtles Tournament Fighters, Leonardo is the Ryu-type while Michelangelo is the Ken-type with faster, multi-hitting attacks (as well as being a Charge Character).
 * Battle K-Road,an arcade-only fighting game released by Psikyo in 1994, features an entire character roster consisting of head/palette swaps. There are two karatekas, two boxers, two Thai kickboxers, two Jujitsu girls, two sumo wrestlers, two commandos and even two Terminator-like cyborgs. The only character without a head-swap is naturally the final boss himself.

Other (unsorted by type) Video Games

 * Kingdom Hearts:
 * Riku and Sora from Kingdom Hearts, until Riku gets lured to the side of darkness and becomes a Rival Turned Evil.
 * And in Kingdom Hearts 358/2 Days, Roxas and Xion play identical to each other, with the exception of Roxas's dual-wield ability.
 * Cloud and Zack from Final Fantasy VII, since  This is a key point in.
 * Tails from Sonic the Hedgehog started out as a Ken to Sonic's Ryu, in Sonic the Hedgehog 2. Since then, Sega did try to slowly differate him, by letting the player actually take advange of his flying ability.
 * Similarly, Sonic Adventure 2 gives three sets of Ryus and Kens (Shadow to Sonic, Eggman to Tails and Rouge to Knuckles)
 * Sonic Heroes kind of went overboard. With Team Sonic as The Ryu, Team Dark as The Ken, Team Rose as the Sakura and Team Chaotix as The Dan
 * Bub and Bob, from Bubble Bobble. Later games in the series did give them (their descendants?) different abilities and personalities, as well as a female-duo Beta Couple in one game.
 * Luigi has often been the Ken to Mario's Ryu throughout the Super Mario Bros.. games, though whatever rivalry is there is questionable. In Super Smash Bros.., they even have the same moves; Luigi gains one unique special and some different normal moves for the sequel (probably so they wouldn't have Luigi, Mario, and Dr. Mario all on the same moveset), but still plays a lot like his brother.
 * In both versions of Super Mario Bros. 2 (the Japanese one known as The Lost Levels outside Japan), Luigi is slightly faster, slightly weaker, and jumps higher than Mario.
 * Ditto for
 * The original Super Mario Kart for SNES had no less than FOUR Ryu/Ken pairs. Mario and Luigi once again played Ryu and Ken to each other (as well as being Jack of All Stats), but Donkey Kong Jr. and Bowser (best top speed), Yoshi and The Princess (best acceleration), and Koopa and Toad (best handling) also formed their own Ryu/Ken pairs.
 * The following Mario Kart games have continued this tradition, with Double Dash!! taking it to somewhat ridiculous levels.
 * Daisy is also a Ken to Peach in her first few apperances in spin off games. She quickly diverged into being diffrent but games like Mario Party and Mario Kart Double dash the two play exactly the same.
 * Similar to the Mario Kart example, characters in Crash Team Racing were paired up by skill: Crash and Cortex (The Marios), Coco and N.Gin (best acceleration), Tiny and Dingodile (best top speed) and Pura and Polar (best handling).
 * Kratos Aurion and Zelos Wilder from Tales of Symphonia use the same weapon types, and have similar stats and identical special moves. With the exception of one single dungeon, however, only one will ever be in the party at a time.
 * Worth noting that the differences between them are more pronounced in the Playstation 2 remake, especially in special moves. Even in the GC version, Kratos has
 * Luke and Asch from Tales of the Abyss, whose move sets are identical apart from Asch having a few offensive spells that Luke doesn't. This is explained as being due to their having learned to fight from the same teacher.
 * Folka Albark and Fernando Albark in Super Robot Wars Compact 3. Even their mechs were originally palette swaps... before they get upgraded.
 * Galaxy Angel II combines this with Expy. Apricot, Milfeulle's younger sister, is Jack of All Stats, just like Milfie was, but for most of the first game, Milfie is retired from the military and is now a Barrier Maiden and Damsel in Distress.
 * Every Fire Emblem game has one of these, known as the Red and Green Knights. They're both Cavaliers who's only difference is stats.
 * In Dungeons & Dragons: Shadow Over Mystara, the Cleric and Magic User classes have slightly different spells in addition to different sprites for player 1 and player 2.
 * As mentioned previously, the Ikari Warriors Ralf and Clark (renamed "Paul" and "Vince") started out as this.
 * Bill Rizer and Lance Bean in the initial three Contra games (including the console ports of the first two). Later installments would have other "Ken's" for Bill's "Ryu".
 * Mega Man and Proto Man.
 * With Bass as the Akuma.
 * Ironically, while Bass is statistically the stronger robot, it is his overconfidence that prevents him from defeating Mega Man.
 * Depending on the game (for example, the Marvel vs. Capcom series), Roll functions as some combo of the Dan/Sakura. Other times, Capcom has her go the Zero route by making her a physically-oriented fighter.
 * Ryu and Ken Hayabusa (son and father, respectively) from the Ninja Gaiden arcade game (or not; no one's really sure. In the arcade game, they're supposed to be nameless)
 * Many of have considered Fox McCloud and Falco Lombardi from the Star FOX games to be this (as noted in the Super Smash Bros. related entries).
 * "Polly and Gon" from Baku Baku Animal
 * Goemon and Ebisumaru (indeed, in "The Legend Of The Mystical Ninja" they were renamed "Kid Ying" and "Dr. Yang" respectively)
 * Squall and Seifer, both being practitioners of Exotic Weapon Supremacy  use similar moves, although with wildy different applications. In fact, these over-similarities are what kept Seifer out of  Dissidia: Final Fantasy .
 * Soul Nomad has Ido/Dio and Yodo/Odie. Storywise, Yodo is Dan to Ido's Ryu, but gameplay makes him Ken. He also cry "Dark Plasma" when doing Thunderbuster, a copy of Ido's Dark Plasma.
 * The original 2 sides from Mount & Blade, Swadia and Vaegir, are such, sharing a troop tree progression. Swadian ranged units use crossbows while the Vaegir's use bows, Swadian infantry uses sword and board and heavy armor while Vaegirs use 2 handed weapons and lighter armor (for quicker speed) and their cavalry shares the defense/power trade off. The stand alone expansion introduces the Sarranids also share a troop tree, who are more focused on speed, making them Sakura type.
 * Pokémon has a few examples. Most are of the appearance kind. For particularly notable examples:
 * Plusle and Minun, who are basically Pichu with plus signs and minus signs respectively for their ears and tails. They also share a type and have slightly differing base stats. They even act as the main partner Pokémon in one of the Ranger games!
 * Latios and Latias, among a few other opposite gender twins, have similar stat distributions (but not the same - Latias has 20 more special defense and 10 more defense, while Latios has 20 more special attack and 10 more attack), and quite similar appearance.
 * Pokémon Black and White Versions have given us the legendary Kami trio: Tornadus, Thundurus, and Landorus. They all look similar, have similar base stats (Tornadus and Thundurus LITERALLY have the same base stats - Landorus has 20 extra defense points, 10 less special attack points and 10 more attack points,) and they all are at least part Flying-type.
 * Charizard and Typhlosion. Exact same base stats, both fire type starters (of regions right next to each other and sharing a Pokémon League, no less) the only difference between the two is that Charizard is part flying type and slightly different movepools.
 * The Devil May Cry series, particularly the prequel (third) game, has the brothers Dante and Vergil.
 * Actually, the trope holds up better in the first game, where Nelo Angelo (aka ) fights using the exact same style as Dante, only while Dante is a more of a Lightning Bruiser, Nelo Angelo is a Mighty Glacier with a BFS who uses a translocation technique to move around the battlefield.
 * Also, to a degree, Dante and Nero in DMC4.
 * Valeria and Anita in Suikoden II. Similar fighting styles and stats, and both own a Falcon Rune. They're also rivals.
 * Warhammer 40,000 has Space Marines and Chaos Space Marines. Chaos Marines are often derisively thought of as mere "spiky marines", due to the fact that they still use largely human weapons, tactics, units, statlines, and even ST Cs. The trade-off is that "Loyalist" Marines get superior technology (Psychic Hoods, Thunder Hammers, Land Speeders, Drop Pods...), while Chaos Marines get daemonic pacts (Cult Marines, Icons of Chaos, sorcerous powers, Daemon allies, mutant specialists...)
 * In the first Sengoku Basara game, Matsu used Kenshin's weapons moveset. Kasuga as well for Sasuke. In later games however Matsu and Kasuga got their own unique moves, the former using a nagitana while the latter used Razor Wire attached to kunai. Similarly, quite a few polearm-using characters used Toshie or Shingen's movesets before getting their own.
 * In Strider 2, Strider Hiryu and Strider Hien. Both use the same techniques, but Hiryu is mostly close-and-personal, while Hien uses throwing weapons.
 * Out of the four playable characters in Panzer Bandit, Kou and Kasumi have a similar set of skills and attacks, though Kasumi is slighty faster and combo-oriented. There's also Jin, who fights identical to Kou.

Real Life

 * Lions and Tigers. Both are big cats of a similar size that kill prey with a bite to the back of the neck. In fiction where the hero is confronted by a big cat, lions and tigers are interchangeable. In Asia, Tigers are also associated with the same characteristics that Lions represent (Pride, leadership, honour etc).
 * Don't forget Jaguars and Leopards.
 * Hawks and Eagles.
 * Lennon and McCartney.
 * Jackie Chan and Jet Li. Back in the 80s, Jackie and Chuck Norris also had this kind of relationship, both training under Bruce Lee.
 * Jackie is the Blue Oni to Norris' Red Oni, but Red Oni to The Stoic Jet Li.
 * Annie Oakley and Lillian Smith. Equally skilled, worked for the same rodeo show for a number of years, and were frequently rivals, until Smith embarrassed herself in front of the Queen of England during an international show and largely retired from active performing soon afterwards.
 * Jeopardy! superchampions Brad Rutter and Ken Jennings are the two highest scoring human contestants in the show's history, each having won over $3 million, while no other human contestant has ever won even $1 million (or anywhere close). Their encyclopedic knowledge and lightning fast reflexes meant they were only ever a challenge for each other and a supercomputer (Brad only ever lost to the IBM supercomputer Watson, and Ken's loss in regular play occurred because he made a mistake in his 75th match. The beneficiary of said mistake proceeded to lose the next match as a one-time champion.)
 * New York City and Los Angeles for the USA cities.
 * There are many modern rifle designs, but the two kings every other rifle will be judged by are the AR15 family and AK family.
 * In firearms cartridges most categories are dominated by two types of cartridges which have very intensely debated comparisons. These are often self reinforcing as their popularity makes their per bullet costs cheap, which makes them popular because their per bullet cost is cheap.
 * .45 Colt and 357 Magnum/38 special for revolvers
 * .45 ACP and 9MM for semi-automatic pistols
 * As an extension of the AR15 vs. AK mentioned above 5.56 and 7.62x39, though 5.45×39 frequently joins in on that.
 * If Remington or Mossberg shotguns were superior used to be a fierce debate. "Used to" because Remington was acquired in 2007 and proceeded to cut quality massively, leaving Mossberg the clear winner.