Ash found Pikachu under the floorboards of his home, chewing on wires to eat the electricity. His mother asks him to take Pikachu outside, but when Gary Oak taunts Ash about how he has not yet become a Pokémon Trainer, Ash decides to keep Pikachu as his first Pokémon.
Ash has Pikachu battle a wildPidgey but it already fled to Viridian City. After finding Pikachu, Ash attempted to put it in a Poké Ball but Pikachu deflected the ball as it disliked being inside of them. While Ash was talking to Misty, Pikachu fled to a grassy field. It defeated a Spearow which caused a whole flock to come. Ash rescued Pikachu from the Spearow and was about to take it to a Pokémon Center until a Fearow arrived. Ash's selfless act of protecting Pikachu caused Pikachu to respect Ash. Despite Pikachu's health being in critical condition, it was able to paralyze Fearow in one blast, giving Ash the chance to capture it. Ash and Pikachu both arrived at a Pokémon Center and Pikachu got healed up there completely.
On their way to a Hidden Village, Pikachu accidentally gets separated from Ash and the others while noticing a Squirtle's shell. Pikachu and Squirtle both go to the Hidden Village in hopes of Ash finding Pikachu. After Damian arrived in the village, looking for his Charmander, Pikachu became determined to find Ash. It found Ash after going down a waterfall.
Pikachu gets exhausted after a battle and rests up at a Pokémon Center. It wanders off after seeing wild Pikachu. The wild Pikachu accept Ash's Pikachu in their group after Ash's rescued a Pikachu with a flower on its head. Team Rocket came by and stole the whole herd save for Ash's who came back and opened the Poké Balls they were contained in. Defeating Team Rocket, Ash's Pikachu planned to stay behind with the other members of its kind but chose to go with Ash when he and his friends were leaving.
At Indigo Plateau, Pikachu meets another Pikachu which belonged to Ritchie nicknamed Chuchino. During Ash's battle with Jeanette, it was the second Pokémon to battle her Bellsprout. Pikachu was unable to use Electric attacks on Bellsprout since Bellsprout used its roots as a ground. Bellsprout threw Pikachu off of its head and was defeated by Bellsprout's Slam. During Ash's battle with Ritchie, Pikachu was used to battle Chuchino after both Squirtle and Ritchie's Butterfree, Happy, were both defeated at the same time. Both Pikachu used the same attacks against each other which also resulted in a double knockout.
Several months later, Pikachu went to the Orange Islands with Ash and they arrived at Valencia Island first. Ash bumped into three punks and his Pikachu easily defeated their Pokémon. Pikachu found a sick Lapras being attacked by a group of Krabby. After healing it, Ash and Pikachu ride on Lapras.
During Ash's battle against Drake, Pikachu was the first Pokémon sent out to battle him where it went up against Ditto. After defeating Ditto, it was not used again for the remainder of the battle until Drake's Dragonite defeated Ash's Squirtle and Charizard. Pikachu defeated Dragonite after crawling in its mouth and launched a Thunder attack, defeating Drake and earning Ash the position as the Orange League champion.
Personality and characteristics
Like in the anime, Pikachu was originally unwilling to obey Ash, but after Ash protects Pikachu from a flock of wild Spearow and a Fearow, Pikachu gains respect for Ash, and after Ash defeats Brock, he is named Jean Luc Pikachu (Japanese: ジャン＝リュック ピカチュウJean-Luc Pikachu).
Pikachu likes Misty and greets her enthusiastically whenever she appears, often ignoring Ash in the process.