Pokémon players prove less is usually better when discussing a competition staple
As with most games, Pokémon battles come in a variety of different formats. The two most well-known formats are Singles and Doubles, but the rules can vary within those formats as well.
For example, all Pokémon VGC matches follow a Doubles format in which you select four Pokémon from your team of six to bring to the battle. Meanwhile, Smogon Doubles has players bring all six Pokémon to battle.