While Ash and Co. continue their journey, they meet Anthony and his Pelipper, which is said to be the world's most powerful Pokémon. The reason is that his Pelipper knows, and type moves instead of only and type moves. How is Ash going to defeat Pelipper, and what are Anthony's Bellsprout, Magby, and Magnemite doing in Pelipper's mouth?
The episode begins with the narrator making flashbacks of Ash arriving into Hoenn, having met May and her brother Max, with Brock reuniting with him on his adventures. Also, the flashbacks also reveal Taillow and Treecko, the Pokémon Ash caught, joining him.
At the present, the gang arrives at Rishin Town where they see a sign that in a Gym is the world's most powerful Pokémon, so they go there. Before they arrive, a man rushes outside, saying he lost to the the world's most powerful Pokémon. The gang arrives to a small field where Ash challenges the trainer to a battle. He introduces himself as Anthony, while Ash wants to battle him. The Pokémon with Anthony is Pelipper.
Anthony says that Ash can use any Pokémon he wants, so Ash brings his Treecko out first. Max explains to May that Pelipper can use only Water and Flying attacks. Pelipper uses Wing, but Treecko dodges the attack. Pelipper uses Vine Whip, much to everyone's shock. Treecko attempts to dodge the attack, but fails. Treecko is defeated, so Ash sends his Taillow.
Taillow attacks with Peck, though Pelipper uses Flamethrower! Taillow is defeated, so Ash sends his ace, Pikachu to battle. Both trainers order to use Thunder attack, making a huge blast! Both Pelipper and Pikachu are injured and cannot fight. Team Rocket appears, seeing the battle. They plan to capture Pelipper, but remind themselves that Pelipper is the most powerful Pokemon, to which they need a more powerful one to capture the Pelipper. Jessie reminds them that they are Team Rocket and they need to steal it.
Anthony takes care to Pelipper, but Team Rocket is flying in their balloon and intimidating Anthony. Pelipper flies to strike, though Team Rocket put special outfits on to protect themselves. Pelipper uses Vine Whip - making Team Rocket use a robot arm to grab the vine, but...
... but catching the vine reveals that a Bellsprout was in Pelipper's mouth! Everything in Pelipper's moth is moving, making him to attack with Water Gun, Flamethrower and Thunder at once. Pelipper is caught, revealing Magby and Magnemite hiding as well in its mouth. James and Meowth condemn him, but Jessie thinks it is genius. Team Rocket order him to give them the Pelipper and do whatever they want with it.
At the Pokémon Center, Max still wants to know how the Pelipper could perform those attacks. Ash's Pokémon are healed and rested. May then takes Ash to another room, where the trainers who fought Pelipper lost and had to give their own Pokémon. Team Rocket persuade others to fight their Pelipper. A trainer comes and brings his Zigzagoon out to fight. Pelipper uses Razor Leaf, Thunder and Flamethrower to defeat Zigzagoon.
The gang is coming to fight, so Mewoth warns Jessie and James. Jessie and James throw more Poké Balls into Pelipper's mouth, even placing Meowth inside. The gang appears, finding the fact that Anthony gave his Pelipper up impossible. Ash brings his Pikachu. Pelipper (with Bellsprout inside) uses Vine Whip, to which Pikachu dodges. Pelipper uses SmokeScreen (with Magby inside) and Razor Leaf (with Bellsprout inside). Then Pelipper (with Magby inside) uses Flamethrower!
Max goes inside, finding Anthony tied. Anthony and Max arrive to the battle. Meowth developes a strategy to defeat Pikachu, so he orders Pelipper to use Water Gun. Accidentaly, it hits everyone, even Team Rocket - unmasking themselves. With Pelipper using Water Gun, it releases every Poké Ball inside its mouth. Anthony discovers his secret, but Team Rocket depart with the Poké Balls. They depart onto the balloon, but Pelipper cuts the rope tied to the bag with Poké Balls, with the gang catching the bag.
Team Rocket dress their anti-electricity suits. Pikachu attacks with Thunderbolt, but the attack is deflected. Max develops the same strategy as Meowth did - Pelipper uses Water Gun on the balloon, with Pikachu attacking with Thunder. Team Rocket is sent blasted away. The Poké Balls are safe, Anthony promises to train Pelipper "the right way" and the gang leaves to Rustboro City.
- "Now put your heads together and come up with a plan." - Jessie to James and Meowth
- The Who's that Pokémon? of this episode is Unown.