Pocket Monsters Stadium had 40 playable Pokémon species.
Nintendo’s Japanese Nintendo 64 game included 3D battle models, but only 40 of the 151 Pokémon from the original Game Boy games could be used in battles. The selection reflected technical limitations and the Pokémon chosen for official Japanese tournaments between 1996 and 1998.
The game’s Pokédex-style viewing function could display information about all 151 first-generation Pokémon, which is why the total playable roster is sometimes mistakenly reported as 151. Viewing a species and selecting it for battle were different features.
Pocket Monsters Stadium also supported rental Pokémon for players who did not connect a Game Boy game. Owners could transfer Pokémon from Pokémon Red, Green, Blue, and Yellow using the Nintendo 64 Transfer Pak. Later international Pokémon Stadium games expanded the available content and are not identical to this Japanese release.