It's a sunny day on the road to Johto when our heroes encounter a Yanma... a troublemaker of a Yanma! When Yanma steals Ash's hat, the gang chase after it as it returns to its trainer, a young boy named Zachary. Although Ash gets his hat back, even Zachary can't control Yanma's antics. After Yanma breaks every window in town with its Sonic Boom attack, Zachary's father forces Zach to return Yanma to the wild. A moment too late, Zachary realizes he can't abandon his friend. Will Zachary be able to find Yanma and learn what it takes to become a true Pokémon trainer?