You Said a Mouthful! (Japanese: 史上最強のペリッパー現る！！The Greatest Pelipper Show in History!!) is the tenth episode of the Advanced Generation series and the 284th episode of the Pokémon anime. It was first broadcast in Japan on January 30, 2003 and in the United States on December 13, 2003.
En route to Rustboro City, Ash and the gang pass by an unofficial gym boasting the world's most powerful Pokémon. Even though he can't win a badge there, Ash is intrigued and decides to battle the trainer named Anthony and this mysterious Pokémon. The world's most powerful Pokémon turns out to be a Pelipper. Pelipper attacks Ash's Treecko with a Vine Whip. It then attacks Taillow with Flame Thrower. Finally, it attacks Pikachu with a Thunder Attack. Ash and crew are amazed—Pelipper should only have Water and Flying type attacks, but somehow it knows Grass, Fire and Electric type attacks! That's not physically possible! Team Rocket decides that they must have this awesome Pokémon, so they, too, challenge Anthony. This time, however, Anthony panics and the truth comes out. Pelipper has been hiding Poké Balls inside its large beak. Rather than being disappointed, Team Rocket decides that this is an excellent opportunity. They blackmail Anthony and use his Pelipper for a new challenge. This time, trainers will lose their Pokémon if they lose to Pelipper. Team Rocket's latest hoax is very successful at first, and they con many trainers out of their Pokémon, but they soon get carried away. They fill Pelipper's beak up with so many Poké Balls that when Pelipper does a Water Gun attack, all of the Poké Balls spill out!
The group enters a new town and spots a sign advertising an unofficial Gym that claims to house the world's most powerful Pokémon. As Ash and his friends arrives, a Trainer rushes his way out, angrily proclaiming that the Pokémon in question wasn't normal at all, making Ash's desire to defeat the Gym grow. As he issues his challenge, a Trainer named Anthony confidently accepts it, along with his Pelipper. Ash takes a moment to check his Pokédex. Anthony explains the rules of the match, he will only use his Pelipper, while Ash may use as many of his Pokémon as he wishes.
Ash decides to lead off with Treecko against Pelipper. Brock has his doubts about Pelipper's world's most powerful status. May turns to her younger brother Max to ask about Pelipper's moveset, and he reveals that Pelipper can only use Water and Flying-type attacks. Pelipper approaches with a Wing Attack and Treecko dodges it. Anthony suddenly tells Pelipper to use Vine Whip, which, as Max points out, Pelipper cannot learn. However, a pair of vines manage to come out of Pelipper's mouth and trip Treecko. Max becomes suspicious of Anthony's battling skills, while Ash is forced to withdraw Treecko for Taillow. It tries to attack with Peck, but Anthony suspiciously orders Pelipper to use Flamethrower, which hits Taillow and knocks it out, much to the shock of everybody, especially Max. Ash calls out Pikachu; when Pikachu uses Thunder, Pelipper is directed to counter with its own Thunder. The attacks collide, knocking both Pokémon to the ground. Anthony tells his Pelipper that it needed a more powerful "Pokémon", before correcting himself and saying "attack" as he carries it off the field. Pikachu is left pretty knocked up, so Ash and his friends rush off to get it treated at the local Pokémon Center.
Meanwhile, Team Rocket plots to steal the Pelipper. They call Anthony out of his Gym and announce their thieving intentions. Anthony orders Pelipper to hit the trio with a Vine Whip, but Meowth uses a grabber claw to catch the attack and a Bellsprout emerges from Pelipper's mouth in the process. Anthony orders a trio of attacks, but the command only confuses Pelipper as it tries to use Water Gun, Flamethrower, and Thunderbolt at the same time. Meowth promptly grabs Pelipper with his mechanical claw as a Magby and Magnemite also fall out of Pelipper’s bill. The Rocket trio instantly see through Anthony’s scheme and call him out for being dishonest. As a result, Team Rocket blackmails Anthony and Pelipper into cooperating on their latest Pokémon stealing scheme.
At the Pokémon Center, as they are waiting for Ash's team to heal, Max becomes convinced that Anthony is cheating somehow, while May dismisses it as the real world not matching up with Max's perceived knowledge. Just then, Trainers begin to pour in, saying that their Pokémon have been taken after losing to the world's most powerful Pokémon. However, Brock suggests that Anthony has been coerced. When the group arrives at the Gym, Jessie and James, disguised as promoters, are announcing a challenge where Trainers have to battle Pelipper, with the winner taking both Pokémon. As Ash accepts the challenge again in order to investigate, starting with Pikachu, Jessie and James become worried, as Pikachu has beaten them numerous times before. As a precaution, Jessie and James place more Poké Balls inside Pelipper's bill, as well as Meowth, who will act as a tactical controller.
As the rematch begins, Pelipper starts with Bellsprout's Vine Whip, which Pikachu manages to dodge. Meowth, inside Pelipper, then switches to Magby for a Smokescreen, but it wells up inside Pelipper's mouth, affecting both Meowth and Magby in addition to Pikachu. As Meowth brings back Bellsprout for a Razor Leaf, Max wanders off and finds Anthony, bound and gagged; he confesses to cheating. Meanwhile, Meowth comes up with a plan to defeat Pikachu by dousing him with a Water Gun, then using Thunder on him to deal more damage. However, because he cannot find any Water Pokémon in the Poké Balls, Meowth chooses to use Pelipper itself to fire the Water Gun. As he does so, Pelipper shoots water everywhere, dousing everyone and exposing Team Rocket's scheme. The Water Gun attack also propels Meowth and all of the looted Poké Ball out of its bill. As Team Rocket tries to escape with the stolen Poké Balls, they are attacked by Pelipper's Wing Attack, which frees the Poké Balls. Team Rocket tries to take Pikachu as a last resort, Pelipper uses Water Gun to soak their balloon. Pikachu follows up with a Thunder, and the combo causes Team Rocket's electricity-proof suits to short-circuit, sending them flying. Afterwards, Anthony ultimately decides to close his Gym down and plans to use Pelipper fairly, as it was powerful even without the Poké Balls in its mouth.