Pokémon Ruby Version, Sapphire Version, and Emerald Version - Double Battle
A Double Battle is a battle with two Pokémon in battle on each side. A Double Battle requires two or more Pokémon. When a Double Battle starts, the first Pokémon on each side takes the left position, and the second Pokémon on each side takes the right position. If there are two Trainers on a single side, instead the first Pokémon on the left Trainer’s party takes the left position of that side, and the first Pokémon on the right Trainer’s party takes the right position of that side.
If a Double Battle has at least one side with two players on it, then it’s called a Multi Battle . In a Multi Battle, each side has two Pokémon on it, with each Pokémon controlled by a different player, and each player can have one to three Pokémon. (In some Multi Battles, one side can have a single player. In such a case, that player controls both Pokémon on a side, must have at least two Pokémon, and can have up to six Pokémon.) In a Multi Battle, when switching out a Pokémon or replacing a fainted one, a player can choose only a Pokémon he or she controls to replace it. However, in Multi Battles that allow the use of the Bag, that player can still use items (such as Potion or Antidote) on a Pokémon the other player controls.