Which Pokémon game first gave players a choice of a female protagonist?

Pokémon Crystal was the first Pokémon game to let players choose a female protagonist.

Released in Japan in December 2000 for the Game Boy Color, Crystal was an enhanced edition of Pokémon Gold and Silver. Its playable female character is commonly known as Kris, while the male protagonist is Ethan in later official naming.

The game also added animated Pokémon sprites during battles, extra story material, and a Battle Tower. Its plot gave greater emphasis to Suicune, which appears on the game's cover and became central to the enhanced version's presentation.

Pokémon Crystal is sometimes confused with Pokémon Gold and Silver because all three games belong to Generation II. Gold and Silver introduced the Johto region, but Crystal was the version that first added player-gender choice to the main series.