Pikachu caused a blackout in Ash's house and was caught by Ash, who had originally planned to release him in the wild, but decided instead to use him as his starter. At first, he was tied to a rope and taken along by Ash on his journey to become a Pokémon Master. He refused to help Ash in catching other Pokémon, and ran away on occasions, only for Ash to find him again. After he was attacked by a flock of Spearow and their leader, Ash rescued him, which caused him to develop a bond with Ash. He fired a Thunder Shock at Fearow, causing it to faint and Misty's bike to get burnt. He showed dislike towards Poké Ball when Ash tried to capture it.
He was used by Ash in his battle against Brock and made a brief appearance during Ash's celebration of his victory. Upon entering the Cerulean Gym, he got scared of Gyarados and refused to battle. Later, he made for to join the battle, only for Misty to lure him to her side by giving him his favorite food. Pikachu and Ash encountered Clefairy while traveling through Mt. Moon and witnessed it evolve during their festival of evolution along with Professor Oak, whom they had met previously, and Bill.
Pikachu encountered Sabrina and Brock in Saffron City. He was used by Ash during his battle against Sabrina and her Abra and tried to attack it multiple times, only for Abra to dodge his attacks and come out unscathed using Teleport. He was defeated after Abra reflected his Electric-type attack back to him. He participated in a battle against Haunter along with other Pokémon to rescue Sabrina, but their combined efforts were proven ineffective against it. He was saved by Abra from crashing onto a wall when Haunter displayed its psychic abilities. He saved Abra from being harmed by Haunter and then carried Abra on his back to counter Haunter's psychic abilities and fired a Thunder at it, only for Haunter to self-destruct itself out of pride.
- Unlike Pikachu's animated counterpart, the manga counterpart of Pikachu; is a wild Pokémon instead of a Starter Pokémon.