Which Pokémon game first introduced a playable female protagonist in the main series?

Pokémon Crystal was the first main-series Pokémon game to introduce a playable female protagonist.

Released for the Game Boy Color in Japan in 2000, Pokémon Crystal was an enhanced version of Pokémon Gold and Silver. Players could choose between a male or female player character, adding a new option to the established role-playing formula.

The game also introduced animated Pokémon sprites at the start of battles and placed additional story emphasis on Suicune, one of the Legendary Pokémon from the Johto region. Its improvements built on the features of Gold and Silver rather than creating a completely new generation.

Pokémon Crystal is sometimes confused with Pokémon Gold and Silver because all three games share the Johto setting and second-generation Pokédex. Gold and Silver introduced Pokémon from Johto, but Crystal was the title that first let players choose a female protagonist in the core series.