Tag Team

A Tag Team is a group of players that take turns fighting, usually one-on-one. A common rule is that, in order to switch, the character must leave the stage and "tag" their partner so they can hop in.

In Video Games, whether or not the characters have separate HP meters is an important consideration -- sometimes the HP meters are shared, and other times they are distinct. A Switch-Out Move may be present, as might a Combination Attack.

Tag-Team Twins is a Sub-Trope. Compare Swiss Army Hero.

Not to be confused with the 1990's rap group who wrote "(Whoomp!) There It Is" and "Pig Power In the House".

Anime and Manga

 * Tag-team matches occur frequently in Kinnikuman, most commonly in the American Tour and Dream Tag Tournament arcs.

Card Games

 * In Yu-Gi-Oh!, one of the most popular and powerful card archetypes are the "Gladiator Beasts," each of which have the ability to swap themselves out on the field for another one after they've battled that turn. This allows the user of such a deck to have enormous, previously unheard-of flexibility. The ability of the Gladiator Beasts is unanimously called "Tagging Out" by the fans.

Film

 * One of the Cars shorts, "Mater's Tall Tales", involves Mater spinning a yarn about once being a monster-truck wrestler. When McQueen interrupts him, he merely brushes it aside with a "Don't you remember nuthin? We was a tag-team!".
 * Top Secret. A Resistance fighter is battling a Nazi soldier in a tag team match inside a wrestling ring (don't ask). The fighter gets in trouble and tags his comrade outside the ring, who then enters and takes out the Nazi. Watch it here, starting at 3:45.
 * The Gamers: Done as a parody, because the male player switches between his testosterone guided "sorceress" into the actual attractive female actress for his character.
 * At the end of Toy Story 3, two of the toys are shown tagging out of the little kids' play area.

Professional Wrestling

 * Every tag team match ever.
 * Professional Wrestling also *averts* this with Tornado tag-team matches, where every participant is legal.

Video Games

 * Art of Fighting
 * Donkey Kong Country: This is how the player switches between Kongs in all games; two-player co-op specifically assigns one player to each respective Kong.
 * Mortal Kombat Deception does this with Noob-Smoke, who share the same life bar.
 * Mortal Kombat 9 has a rounded Tag Team mode.
 * Every Marvel vs. Capcom game, starting from X-Men vs. Street Fighter all the way up to Marvel vs. Capcom 3. Also Tatsunoko vs. Capcom.
 * The Naruto Clash of Ninja fighting games feature "Two-Man Squad" battles where each side fights in a tag-team manner, with the characters on standby regenerating their lost chakra and (some of) lost HP. Story-based missions which require a particular finishing move means We Cannot Go on Without You if that character becomes KO.
 * In Paper Mario and Paper Mario: The Thousand-Year Door, the player could switch Mario's partner at any time, but doing so typically required one turn.
 * In regular Pokémon battles you can have a team of up to six pokemon but only one Pokemon is present in battle at a time; switching Pokemon requires a full turn (allowing the opponent a free strike). Later generations introduce a small number of two-on-two and three-on-three battles to mix things up.
 * The fifth generation also introduces "rotational" battles, three-on-three battles where only one pokemon on each team can participate at a time, but switching between them is a free action.
 * Skullgirls, in the same way that it works in Marvel vs. Capcom.
 * Soul Calibur 2 has a team battle mode where you fight with multiple characters, but you only switch when your current fighter is defeated.
 * The Super Smash Brothers franchise features a team-battle mode, which let players put themselves into one of three teams, including red, blue, and green, so that each player can work together with the other(s) to defeat their opponents. While there are two-on-one fights, three-on-one fights, and two-on-one-on-one fights, the most fair team-fight of them all tend to be two-on-two fights. There isn't any tagging per se, but even then, they are still team-battles.
 * The Pokémon-Trainer doesn't do all the fighting himself, but can switch between each of his three Pokemon during combat, including Squirtle, Ivysaur, and Charizard (in that order). However, all three of the trainer's Pokemon share the same damage-meter, meaning that switching Pokemon doesn't change the meter's damage-percent.
 * The Ice Climbers, Popo and Nana, can both be controlled at the same time, and can deal and absorb more damage when they're together. However, when the AI-controlled ice-climber dies, the player-controlled ice-climber's capabilities decrease drastically.
 * Captain Olimar of the Pikmin fame can utilize his army of pikmin for various attacks, much like in his own game-franchise. His pikmin can still die like in the Pikmin franchise. Thankfully, though, Olimar can just pluck new Pikmin any time the player controlling him pressed B to do so.
 * While Zelda and Shiek are actually the same character, they can still be switched between during each match to access one of two different ability-sets. Despite their lightweight, Zelda's magic possesses more damage-capacity, while Shiek's physical-attacks are much faster.
 * Tekken Tag Tournament
 * And, of course, the long-awaited upcoming sequel, Tekken Tag Tournament 2.
 * Street Fighter X Tekken
 * Viewtiful Joe 2: Joe and Sylvia share the same HP meter, physically tag in and out, and holding down the tag button results in a damaging Combination Attack.
 * In Kizuna Encounter: Super Tag Battle, both characters have separate HP meters, and the round ends when one is depleted, no matter how much HP the partner has left.
 * Dead or Alive, starting from the second game, has a tag mode.
 * Some entries in The King of Fighters series have modes where characters can be swapped in and out of battle.
 * In the Warriors Orochi series, you form a team of three fighters, and while each of them has their own life meter, the game is over if any one of them is defeated by the enemy.
 * "Dramatic Change" mode in the Wii version of Shikigami no Shiro III. One player controls two characters who share a life meter but can be switched in and out at any time.

Western Animation

 * The Simpsons go to Japan and attend a Sumo wrestling match; Homer gets in a scuffle with one of the sumo wrestlers, then Bart tags in and uses a folding chair on the sumo wrestler.