Following the end of Satoshi's Hoenn journey, he travels to the Sinnoh region for his next adventure en route to becoming a Pokémon Master. Immediately upon arrival, Team Rocket makes another attempt to snatch Pikachu, only for it to fail once again. However, Pikachu has fallen deep into a forest and it's up to Satoshi to find him! Along the way, he reunites with Takeshi—a Pokémon breeder with whom he has traveled through many regions—and meets his soon-to-be rival, Shinji, a power-hungry trainer who cares little for his Pokémons' feelings.

Still in search for Pikachu, Satoshi notices a powerful electric attack in the distance and heads toward it to find Pikachu with Team Rocket and Hikari—a novice trainer aiming to be the top Pokémon coordinator. After foiling Team Rocket's plans, Satoshi reunites with Pikachu and Hikari joins the group. And thus, Satoshi and his friends begin their journey through the exciting land of Sinnoh.