Opponent Switch

Our group of heroes are fighting against the Psycho Rangers, Evil Twins or opponents skilled or specialized against certain techniques against them, individually, fighting to, at best, a stalemate. One of the heroes realizes it's futile fighting against their equal, so all of them switch opponents, which wins them the battle. For some reason this almost never leads to Evil Twin A being defeated by Twin B but Evil Twin B defeating Twin A, as might be expected if they're actual equal to their doubles, nor the evil ones winning due to the change. There just seems to be some rule that switching opponents automatically guarantees heroic victory, even if it doesn't make sense. A common subversion of the Plot Tailored to The Party. May be justified in that the villans use techniques that are only useful against their chosen enemy, meaning they would be useless against anyone else. Another justification that makes more sense is that the heroes don't know their own weaknesses as well as they know those of their teammates, so when they switch, their teammates know the weaknesses of their teammate and thus the Evil Twin they're up against and can thus defeat them.

Compare Counterpart Combat Coordination.

Anime & Manga

 * Bleach: Uryu and Chad switch opponents in their first battle in Hueco Mundo and successfully defeat them. Note that it also went in an opposite direction: initially, the speedy archer Uryu was fighting against a giant and The Big Guy Chad has been fighting against a fast shooting Arrancar. Then they switched to Mirror Match of sorts, by fighting opponents strong in the same fields as they - and completely overwhelmed them.

Comics

 * A backup story in Peter Porker, the Spectacular Spider-Ham has the Fantastic Fur meet an evil set of themselves, and they predictably go after their doppelgangers as per usual. Then the Reed Richards says that they should change opponents -- so the Thing fights the Invisible Girl and Reed fights the Torch -- then the Thing gets an idea... rather than fighting each other, they should fight the bad guy versions of themselves.
 * This is actually used quite often in comic books. For example, the Fantastic Four did the same trick decades earlier than the above Peter Porker example in one of the Silver Age Galactus stories, and in another Silver Age story involving robot doubles fighting them.
 * Inverted in another early story when they were up against elemental constructs. The elementals were under strict instructions from their creator to avoid going up against their opposite numbers (Reed/Water, Sue/Air, Thing/Earth, Torch/Fire) and each ends up being defeated by its counterpart.
 * This was part of the premise of the Marvel Comics crossover Acts of Vengeance.
 * Inverted in the very first Justice League story featuring the Crime Syndicate of America: there, the JLAers only won when each member took on their specific counterparts with a series of Overclocking Attacks.
 * This happened in one issue of Archie's Sonic the Hedgehog, where Sonic and the Freedom Fighters fight their evil mirror universe doppelgangers.
 * When the Thunderbolts were ordered by the government to rough up the New Avengers (who were looking into things they didn't like), the Avengers tried to do this, only to find out the Thunderbolts had predicted it.
 * Runaways does this during the final fight of the first volume, when the kids confront their parents. Gert's dinosaur companion Old Lace is incapable of attacking any of her family, and Karolina's family's powers don't work on each other. "Ready... set... switch!"
 * The X-Men do this in The Dark Phoenix Saga. Colossus, Storm and Wolverine find themselves facing three of the Hellfire Club's Elite Mooks with power armors customized for their individual powers. Switching things up works nicely.
 * In the original Young Justice comic, they're up against fake nemeses; Robin versus Joker, Superboy versus Metallo, Impulse versus Grodd. Robin works out that they need to switch. He beats Metallo, Superboy beats Grodd, and Impulse...is so annoying that he drives the Joker nuts with frustration.

Literature

 * Happens in the Batman Cold Open of one of the Nightside novels, when John Taylor and Susie Shooter battle their Mirror Universe opposite-sex counterparts, Joan and Steven.

Live Action TV

 * Denji Sentai Megaranger/Power Rangers in Space did this with the Nejirangers / the original Psycho Rangers. To elaborate: each Psycho Ranger had absorbed the fighting knowledge of his/her opposing Power Ranger, and was thus able to properly defend and retaliate. At first, the Power Rangers did the normal "switch opponents" variant, but since the rangers were Color Coded for Your Convenience, the Psychos just found their Rangers again and switched back. Then the Power Rangers went in all dressed like the Blue Ranger...
 * And then the Psychos memorized each Ranger's voice so they wouldn't fall for that trick either. Possibly the most justified case for a show not going with this trope for more than one episode.
 * Also happens in Seijuu Sentai Gingaman/ Power Rangers Lost Galaxy. Copis/Chameliac, a Monster of the Week that is able to copy and counter the rangers' fighting style gets outsmarted when the rangers switch fighting styles with eachother, confusing the monster. Then, in the Megazord fight, he copies the Megazords' powers as well. When the Stratoforce Megazord shows up, he copies it...only for it to use this trope by pulling out the Centaurus Megazord's gun and shooting him.

Tabletop Games

 * Champions supplement Red Doom. One of the Supreme Soviets' standard combat maneuvers was "Soccer Ball", in which the team members switched opponents until they found one that was vulnerable to their attacks.

Toys

 * Bionicle: How the Toa Mata defeated their Psycho Rangers counterparts in Tales of the Masks.
 * Each year there are also frequently a set of enemies who are similarly color coded, such as the Bohrok, the Rahkshi, the Vahki and so on. However the Toa don't generally express any particular desire to specifically go after their same color counterparts.
 * The encyclopedia canceled it, however: the Toa understood that the Psycho Rangers were actually their inner evil, and reabsorbed them by accepting it.

Web Comics

 * Subverted in Order of the Stick. When the Linear Guild is failing to make progress against the Order, Nale suggests to Thog that they trade opponents. This actually makes things worse, as Elan's normally useless bardic magic is effective against Thog, and Roy has been holding back a strong urge to beat the tar out of Nale's twin brother Elan for quite some time.
 * The Linear Guild strikes again much later. With Roy getting the tar kicked out of him by Thog, Elan fleeing Nale, and V unable to get through Zz'dtri's magical defences, V then realises that Zz'dtri's achilles heel is best countered by someone else and invokes this trope - by using the Guild's own archer specialist, to boot.

Web Original

 * "Ayla and the Great Shoulder Angel Conspiracy" in the Whateley Universe: when fighting New Olympians best suited to combatting them (even Person of Mass Destruction Tennyo), Team Kimba manages to trade opponents one by one until they defeat enough opponents that they can double-team the last couple.

Western Animation
"Cyborg: Told you I could kick your butt."
 * Happens in Xiaolin Showdown, when a Sheng Gong Wu creates physical manifestations of each warrior's worst fear.
 * In Justice League Unlimited, when pits the League against their own Evil Twins, The Flash, Batman, and Martian Manhunter are able to defeat their doubles on their own, while the rest eventually switch opponents. Leads to an amusing exchange between Green Lantern and Hawkgirl, who both comment that the other one enjoys whacking their opponent a little too much.
 * Teen Titans: Cyborg, Beast Boy, and Starfire fight against their Psycho Rangers counterparts, switching in the end to defeat them (Starfire to Evil Cyborg, Beast Boy to Evil Starfire, and Cyborg to Evil Beast Boy).


 * In the Fox series, the X-Men once fought their evenly-matched counterparts in X-Factor until Beast suggested they switch.
 * One episode of of the 2003 Teenage Mutant Ninja Turtles had Baxter Stockman create a Turtle Robot that scanned each of the TMNT as they went to attack it, once scanned the robot could replicate their weapons and fighting style, which worked, until the TMNT switched weapons with each other.
 * A Season 3 episode of Batman the Brave And The Bold features the villains setting this up in order to get the upper hand against their respective Arch Enemy. The Joker fights Wonder Woman, Cheetah deals with Superman, leaving Lex Luthor with Batman.
 * Inverted in an episode of The Powerpuff Girls where three crooks dress up as the Powerpuff Girls. When the Girls and the crooks throw down, both sides end up attacking their teammates by mistake before Blossom says they should just fight their counterparts to keep things simple. The whole episode is taken into Refuge in Audacity territory because the crooks' disguises are blatantly obvious to the viewer and yet everyone including the real Powerpuff Girls and the crooks still confuses them for the real thing.
 * The Re Boot Episode Wizards Warriors and a Word From Our Sponsors has Bob, Dot, Enzo and Mike the TV fight off their evil doppelgangers in a fantasy game. It doesn't go well until Mike inadvertently switches opponents by bumping into Evil Dot (who runs screaming from Mike's incessant infomercials).