Which main-series Pokémon game first let players choose a boy or girl protagonist?

Pokémon Crystal was the first main-series Pokémon game to let players choose a boy or girl protagonist.

Released for the Game Boy Color in Japan in 2000, Crystal is an enhanced version of Pokémon Gold and Silver. Earlier main-series games used a fixed male protagonist, while Crystal added the female option represented by Kris, known in Japan as Chris.

The choice changes the player character’s appearance and sprite, but it does not create a separate storyline or alter the major events of the Johto adventure. The game also introduced animated Pokémon sprites at the start of battles, giving the creatures more visual motion than in Gold and Silver.

Later remakes expanded the idea with more customizable protagonists and character designs. The female option in Crystal is therefore historically important, even though modern Pokémon games offer much broader player customization than the original Game Boy Color title.