Which enhanced Game Boy Pokémon game featured Pikachu as its mascot?

Pokémon Yellow was the enhanced Game Boy Pokémon game that featured Pikachu as its mascot.

Released in Japan in 1998 and internationally from 1999, Pokémon Yellow was designed to resemble the popular anime more closely than the earlier Red, Green, and Blue versions. Pikachu followed the player character rather than remaining inside a Poké Ball at the start of the adventure.

The game also adjusted several characters and encounters to echo the television series, including the availability of Bulbasaur, Charmander, and Squirtle through story events. It used the Game Boy Color’s palette while remaining compatible with the Game Boy family.

Pokémon Yellow is sometimes grouped with the second-generation games because of its later release date, but it belongs to Generation I. Pokémon Crystal, Emerald, and Platinum were later enhanced versions associated with Generations II, III, and IV respectively.