From Bulbapedia, the community-driven Pokémon encyclopedia.
A Full Battle (Japanese: フルバトル full battle), also known as a six-on-six battle, is a Pokémon battle in which both Trainers use a full party of six Pokémon. The first Trainer to completely knock out all of the opposing Trainer's Pokémon wins the battle.
These battles are rare, both in the anime and the games. Typically, Trainers will use fewer than the full six, usually one to three.
In the anime
Most Trainers declare a specific number of Pokémon to be used in a battle. This number is very rarely the full six. The most notable Trainer to do so is Drake, the Head Leader in the Orange League. Battles in the final rounds of each region's League Conference are usually full battles as well.
List of full battles
In the games
Unlike the anime, the games allow two Trainers to use different numbers of Pokémon. While the player can have six Pokémon in the party at a time, many NPCs faced will not. Generally only rivals and Champions have a full team during the main storyline, while Gym Leaders* and members of the Elite Four* may also have a full team in rematches. Some Pokémon Breeders also maintain a full team, although it is usually weaker than other Trainers in their area. Most main series games have at least one Fisherman with a party of six Magikarp. Only on rare occasions do other Trainers have a full team.
- The Diamond & Pearl series is the only series in which a full battle took place outside of the Pokémon League.