Pikachu is Ash Ketchum’s constant companion in the original Pokémon anime.
Ash receives Pikachu from Professor Oak in the first episode, “Pokémon, I Choose You!”. Pikachu initially dislikes staying in its Poké Ball and does not trust Ash, but their relationship changes after Ash protects Pikachu from attacking Spearow. Their partnership becomes the emotional center of the series.
Ash’s other Pokémon change as he travels through different regions, but Pikachu remains with him. That consistency helped make Pikachu the most recognizable character in the franchise and its principal mascot. Pikachu’s small size, expressive design, and electric attacks also made it suitable for animation and merchandise.
Ash and Pikachu are not the same as the player character and starter Pokémon in the original Game Boy games. Ash was created for the anime, while the games provide a player-controlled trainer. The anime’s Pikachu also differs from ordinary game mechanics because it regularly behaves as a named character with a distinctive personality.