With the Sinnoh League behind them, Ash and friends take a ship back to Dawn's hometown of Twinleaf. A crisis emerges, however, when a group of Tentacruel attack the ship and poison many of the Pokémon on board. With no other doctor on the ship, Brock is the only one who can help those Pokémon. Will he succeed before it's too late?
A young boy named Ash Ketchum embarks on a journey to become a "Pokemon Master" with his first Pokemon, Pikachu. Joining him on his travels are Brock, a girl-obsessed Rock Pokemon Trainer, and Misty, a tomboyish Water Pokemon Trainer who may have a crush on him. Ash and Co. end up traveling through various regions, including Kanto, the Orange Islands, and Johto, and then enter the Pokemon League competitions there.
Along the way, they run into many confrontations with Jessie, James, and Meowth, a trio of Pokemon thieves who are apart of an evil organization called "Team Rocket". But every time Team Rocket try to do their evil deeds, they fail thanks to Ash and his Pokemon.