Which Pokémon games introduced double battles?

Pokémon Ruby and Sapphire introduced double battles to the main Pokémon video-game series. In this format, each side can have two Pokémon active at the same time.

The games were released for the Game Boy Advance and began Pokémon’s third generation. Double battles added new tactical considerations because moves could target one opponent, both opponents, an ally, or the entire field depending on the move.

Ruby and Sapphire also introduced Pokémon Abilities, Natures, Pokémon Contests, Secret Bases, and the Hoenn region. These systems expanded the series beyond the one-on-one battles that had defined the first two generations.

Double battles are different from multi battles. In a double battle, one Trainer generally controls two Pokémon. In a multi battle, two Trainers may fight on the same side, with each controlling Pokémon. Later games built on the mechanic with formats such as Triple Battles and Rotation Battles.