From Bulbapedia, the community-driven Pokémon encyclopedia.
This is a list of all of the Johto rental Pokémon in Pokémon Stadium 2 sorted by National Dex number. Unlike Pokémon Stadium, most of the available rental Pokémon are the same or similar across most battle modes (other than Little Cup), but there are a few differences depending on the level bracket or Round.
Poké Cup/Gym Leader Castle
Prime Cup/Anything Goes
In these battle modes, every rental Pokémon is level 100 and their stats are adjusted accordingly. Stat Experience is slightly adjusted for some Pokémon, but otherwise most rental Pokémon are identical to their level 50 counterparts. Several Pokémon's movesets do differ, however, and those Pokémon are listed below. Most of these changes involve moves that the Pokémon in question would learn by leveling up after level 50 in Generation II.
Celebi is also available as a rental, but only in Round 2 of the Prime Cup.