Erika's Raichu is the sixth Pokemon she obtained. She first appeared as an Pichu in Pichu's Picnic.
Raichu first appeared as an hungry Pichu who was looking for food and Erika offered her food which made her follow Erika around. Knowing that Pichu can evolve into a Pikachu, Team Rocket trapped Pichu and was planning on stealing her so they can evolve her into a Pikachu and take her to the boss for a big payment. Erika rescued the little Pichu and sent Team Rocket blasting off. In another episode, Pik and Erika's Pichu were captured by Team Rocket as Team Rocket called them a bargain for the boss, but they were rescued by their trainers. Pichu loves to show off in Pokemon showcases with her trainer. During a showcase, Pichu evolved into Pikachu. While exposed to a Thunder Stone, Pikachu evolved into Raichu.
Raichu as an Pichu first appeared hungry and was looking for food. When Erika helped her, Pichu wanted to show her much she wanted to be her Pokemon. After Erika rescued her from Team Rocket, she accepted to take Pichu with her on her journey and caught her. Pichu like the rest of Erika's Pokemon is loyal to her trainer and tries to impress her. Erika takes good care of her and trains her. She loves showing off in Pokemon showcases. Pichu and Plusle are best friends and like to play together. She evolved into Pikachu during a showcase. During the 2nd season of Gabe's Kalos Pokemon Adventures, she evolved into Raichu while exposed to a Thunder Stone. Now an fully evolved Raichu, she stills loves to show off in showcases.