From Bulbapedia, the community-driven Pokémon encyclopedia.
[[Pokémon Stadium (English)|Pokémon Stadium ]], up to four people play together with only one available CPU player. Players have the option of setting the CPU's difficulty to either Easy, Normal, or Hard. Players form teams each choosing 3 Pokémon, and they decide who goes first by selecting their Pokémon first on the selection screen. Pressing L will reset all players' Pokémon choices on the selection screen, allowing them to choose again. Holding the R button will allow the player to check which Pokémon they have selected alongside their partners on the selection screen. Players use the A, B, and C buttons to select the Pokémon they will use. Once all six have been chosen, the battle will begin.
As [[Double Battle|Double Battles]] did not exist in the first and second generations, if more than two people play, up to two will be on a "team". Each player on such a team will choose six of either their own Pokémon from either a Pokémon [[Pokémon Red and Blue Versions|Red]], [[Pokémon Red and Blue Versions|Blue]], or [[Pokémon_Yellow_Version|Yellow]] game inserted into a [[Transfer Pak]] that is connected to their controller, or they may choose from a selection of the rental Pokémon available to them. During the team preview, each of these two players may choose three of the Pokémon they wish to enter in that particular battle. Players will only have control over the Pokémon they selected. In order to switch to a teammate's Pokémon, that teammate must press B to switch to another Pokémon, and then press the corresponding C button, depending on which Pokémon they want. A player can only switch to their own Pokémon.