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 Pikachu. While bonding, Goh threw a Poké Ball at her and successfully captured her. She proceeds 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.
Raichu and Goh
In Healing the Healer!, Goh managed to catch an injured Suicune that a group of Pokémon hunters were trying to capture. After escaping, Raichu helped collect some Berries to help Suicune recover.
In JN070, 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 JN073, 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 has 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 find the missing Falinks.
Personality and characteristics
Raichu feeding Goh's other Pokémon
In the daily life of the laboratory, 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. 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.
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 Laboratory. Raichu again uses this skill to help motivate a Falinks by guiding her teammates.