Which main-series Pokémon game first allowed players to choose a female playable character?

Pokémon Crystal was the first main-series Pokémon game to let players choose a female playable character.

Earlier games provided a single playable protagonist, generally presented as male. Crystal expanded the character-selection system by adding Kris, the female player character, alongside the male option. The choice changes the player's appearance and name but not the central adventure.

Crystal is an enhanced version of Pokémon Gold and Silver for the Game Boy Color. It retains the Johto setting and the ability to visit Kanto, while adding story emphasis on the Legendary Pokémon Suicune, animated Pokémon sprites, and other presentation changes.

The feature became standard in later main-series Pokémon games. It is sometimes confused with Pokémon Yellow, because Yellow changed the starter experience and followed anime-inspired ideas, but it did not offer a female player character. Crystal's character choice was therefore an important milestone for player representation in the franchise.