The kids are running for the ferry to Lilycove and jump on the boat they see leaving, only to discover it's actually a boat to Bomba Island. Once they arrive on the island, they meet a young Trainer named Jimmy and his Wartortle, Charmeleon and Ivysaur. Jimmy is a student at the Pokemon Battle Judge Trainin Institute, located on the island.
Professor Serena from the institute gets Ash and Brock to help out in her class by staging a Double Battle which Jimmy will judge. Ash uses Swellow and Corphish, while Brock uses Mudkip and Lombre. The battle is fierce, and after Mudkip and Lombre both use Water Gun on Corphish simultaneously, Jimmy mistakenly declares Corphish unable to battle.
That night, Ash and friends find Jimmy outside talking to his Pokemon. Jimmy explains how he met all three of them by accident, and even got a Cascade Badge--also by accident. Team Rocket interrupts and takes all three of the Pokemon, causing Jimmy to run after them. Seeing his determination, Wartortle evolves into Blastoise and uses Hydro Pump to free the others. Team Rocket is the defeated as usual.
Serena tells Jimmy that he has to leave school now, but not because he's a bad student, but because he'd make a better Trainer. Jimmy heads back to Lilycove to start his Pokemon journey over, while Ash and friends continue on to Mossdeep City.