Raichu, as a Pikachu, first appeared in Gotta Catch a What?! living alongside a hoard of other Pikachu and Raichu. She discovered Goh, Ash, and Ash's Pikachu while Goh searched for a Pikachu to capture and quickly became friends with Ash's. While bonding, Goh threw a Poké Ball at her and successfully captured her. She proceeded to shock him with Thunderbolt after being called back out.
Soon after, Pikachu discovered a Thunder Stone. She teased Ash's Pikachu by chasing him around with it before giving the stone to Goh. Right after, Team Rocket showed up and began stealing the Pikachu and Raichu, including Ash's. Goh's Pikachu volunteered to save them, and in the process touched the Thunder Stone and evolved into Raichu. With her new strength, she freed her friends and joined them in blasting Team Rocket off.
In Take My Thief! Please!, during a confrontation between Goh's Greedent and Morpeko, Raichu handed the two a large amount of Berries to calm them down. Goh took advantage of this to try to catch Morpeko, but failed. Later, Raichu was seen helping handing food to Goh's other Pokémon, including bringing some to his secluded Drizzile.
In Grabbing the Brass Ring!, Raichu joined Goh's Pokémon to help motivate the brass leader of Falinks when it became separated from its troops. Raichu offered everyone Berries and had them work together to act as a temporary replacement for the troops. During the attempts, Raichu used her tail to guide Goh's Cinderace into the group, who was having difficulties. Soon after, they found the missing Falinks.
In This Could be the Start of Something Big!, Raichu was seen helping out at a surprise party thrown by the Laboratory members for Goh and Ash to commemorate their departure.
In the daily life of Cerise Park, Raichu is the Pokémon responsible for feeding the other Pokémon that live there. Raichu is a very docile and friendly Pokémon; whenever she finds some Berries or items she offers them to other people and Pokémon, most notably for Pikachu. Even when they refuse, she is insistent on offering something to them. In Suffering the Flings and Arrows!, Raichu was the first Pokémon to interact with the newly caught Goh's Lilligant, offering her a Berry, proving to be quite receptive to new Pokémon arriving at the Laboratory. Raichu has a special affection for Ash's Pikachu, either interacting with him while eating, or giving items specifically to him.
When Team Rocket captured the other wild Pikachu, she volunteered to evolve herself so that she could save them. Later, Raichu's knowledge of Berries proved useful when Goh’s newly captured Suicune had been badly injured after an encounter with a gang of Pokémon Hunters.
Raichu is seen as a peacemaker, promptly resolving the conflict between Greedent and Morpeko. This is seen again later when she replenishes their food the next day, though Morpeko had already left the Cerise Laboratory. Raichu again uses this skill to help motivate a Falinks by guiding her teammates.
In celebration of the airing of JN100, the Pokémon anime's Twitter page launched a series of audio dramas. In the second one, Nighttime at the Sakuragi Park, Raichu is mentioned by Ash while sleeping together with Pansear and Panpour.[4]
Trivia
The Thunder Stone Pikachu used to evolve
Her capture marks the first time a main character other than Ash has obtained a Pikachu.
