Ash Ketchum’s first Pokémon in the original anime series is Pikachu.
In the first episode, Ash oversleeps and arrives too late to choose one of Professor Oak’s standard starter Pokémon. Oak gives him Pikachu instead. Pikachu initially resists Ash’s commands and refuses to stay inside its Poké Ball, creating a difficult start to their partnership.
Their relationship changes after Pikachu protects Ash from a flock of Spearow. Ash risks himself to shield Pikachu, and Pikachu responds by unleashing a powerful electric attack. The event establishes their friendship and makes Pikachu Ash’s permanent companion.
The anime’s version differs from the games, where players normally choose Bulbasaur, Charmander, or Squirtle at the beginning of Pokémon Red, Green, and Blue. Pikachu is also the player’s partner in Pokémon Yellow, which was inspired by the anime’s popularity.