On their way to Hearthome City, Ash & Co. meet up with Aaron, one of the Elite Four of Sinnoh. When they meet up with him, they see Aaron is training both himself and his bug Pokémon. However, he is in the area since he's looking for a Wurmple he let go. Ash & Co. offer to help, however Team Rocket are in the area trying to steal some Pokémon. Can Ash & Co. find the Wurmple?