Tag-Team Duel

A Tag-Team Duel (also known as a 2v2 Duel) is exactly like a normal Duel, but four players are playing at once. Two players team up to form a "Tag Team"-style group. Both teams begin with 8000 Life Points between both players and all other rules apply.

Rules
When taking part in a Tag-Team Duel both Teams must consist of 2 players. Players can either share a combined life point total of 8000 or individual life points of 8000 each. Players may share their fields of have their own individual fields. Neither player can look/use at their team-mates or their opponents hands or set/Faced-down cards. If one member of a team has been defeated thats members deck and field is unusable.

Video games
Alternatively, players can play in a style similar to Tag Dueling in various video games, such as the World Championship and Tag Force series. Both players share 5 Monster Card Zones, five Spell & Trap Card Zones, Graveyard, Banished Zone and Field Card Zone. The Duel proceeds like a normal Duel, with the Main Deck, Extra Deck, and hand changing as each teammate becomes the new turn player of the team at the start of every other turn. Any player-specific cards will only affect the turn players of each team at the moment.

Yu-Gi-Oh! (DM) & Yu-Gi-Oh! GX
The first Tag Team Duel in the anime was Joey Wheeler and Yugi Mutou vs. The Paradox Brothers. There have also been occurrences of 2 vs. 1 Duels (e.g Yugi and Kaiba vs. Dartz), 1 vs. 3 Duels (Tristan, Serenity and Duke vs. Nesbitt in the Virtual World Arc), 1 vs. 5 Duels (Chazz vs. 5 North Academy pupils in Yu-Gi-Oh! GX), and even 2 vs. 5 duels (e.g Yugi and Joey vs the Big Five in the Virtual World). The tag-team rules also change between instances: some duels give each team a shared Life Points count like in the real world (in Yu-Gi-Oh GX there was such a Duel, but with an 8000 Life Points pool per team, instead of the standard 4000 in the series ), while others give each player a his own Life Points and if one players loses all Life Points, the team loses. There are also some Duels that worked similarly but allowed one player to keep going even if their partner is defeated. In Yu-Gi-Oh GX Season 4, the Tag Duels were played similar to how it was done in World Championship 2008 (see above).

Yu-Gi-Oh 5D's
These rules have been also used in the Yu-Gi-Oh! 5D's series, when Crow Hogan and Yusei Fudo team up to face off against Sector Security. Furthermore, even though it took place through a Turbo Duel, the 2008 World Championship rules weren't changed. In the series it has been revealed that this type of Team Dueling is supported even on the world of Turbo Dueling. As there has been shown in the anime the existence of special Duel Runners for Tag team duels.

A 3-on-1 Tag Duel happened from episodes 62 to 64. Rex Goodwin, who was alone, started with 3 times Life Points, 12000. Yusei Fudo, Jack Atlas and Crow Hogan had separated fields, Decks and Life Points. Effects of cards used by Rex that targeted the opponent player targeted only one of the three, by his choice.

Also, in other instances according to the canonical movie 'Yu-Gi-Oh! 3D Bonds Beyond Time' during the 3 vs. 1 duel between Yugi, Yusei and Jaden vs Paradox, tag-team players are able to share cards on the field. An example of this is displayed when Yusei allowed Yugi to use Reincarnation of Hope's effect or when Jaden borrowed Junk Gardna to fuse with Elemental HERO Neos to summon out Elemental HERO Neos Knight.

In addition, spells or traps can be used to effect monsters that under your partner's control.

Yu-Gi-Oh! ZEXAL
In Yu-Gi-Oh! ZEXAL, a Tag Duel is seen in episode 11, only with a rule set similar to Yugi's and Kaiba's Duel in Battle City; all 4 players have separate Life Points.

Another one is seen in episode 37, but this time it was a 2v1 match, all players with separated Life Points, and if one player lost, his/her partner would lose as well. It's also seen at episode 42 where Yuma and Kite Duel against III and Quatro.

Tag-Team specific cards
Some anime-only cards in the anime can only be used in a Tag Team Duel:


 * Reflector Bit
 * Side Attack
 * Lightning Talisman
 * Revolving Stage
 * Masquerade
 * Bit Shoot
 * Partner Change
 * Card Exchange
 * Wish of Final Effort (Does not have to be activated in a Tag-Team duel, just has different effects when played in a Tag-Team duel).
 * Final Offering