Pikachu was number 025 in the original National Pokédex.
Pikachu’s official Pokédex number is 025, placing it after Raichu’s earlier evolutionary entry and before Sandshrew. It is an Electric-type Pokémon first introduced in the Generation I games.
Although Pikachu was not the player’s only possible starting Pokémon in the original Red and Green games, the animated series made it the most recognizable Pokémon by assigning it to Ash Ketchum. Its yellow design, pointed ears, and electrical cheek pouches became central symbols of the franchise.
Pikachu’s popularity also influenced later game design. Pokémon Yellow placed Pikachu beside the player from the beginning and drew more directly from the television anime than the original Red, Green, and Blue versions.