Which Pokémon game was the franchise's first Nintendo 64 release?

Pokémon Stadium was the franchise's first Nintendo 64 release.

The game was released in Japan on August 1, 1998, and brought Pokémon battles into a 3D arena. It focused on tournament-style combat rather than the exploration and catching structure of the Game Boy role-playing games.

The Japanese version originally supported only a limited selection of Pokémon. The international release, titled Pokémon Stadium, expanded the playable roster to 151 Pokémon and included features that connected with Pokémon Red, Blue, and Yellow through the Transfer Pak.

Pokémon Snap also appeared on Nintendo 64, but it was released later and centered on photographing Pokémon. Pokémon Stadium 2 was a sequel rather than the first Nintendo 64 entry. These related titles are the main reason the franchise's early Nintendo 64 history can be easy to mix up.