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!
Ash and his friends arrive at an unofficial Gym that claims to house the world's most powerful Pokémon. As the group 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 such a Pokémon grow. As he issues his challenge, a Trainer named Anthony arrives to accept it, along with his Pelipper. The rules of the battle dictate that Anthony will only use his Pelipper, while Ash may use as many of his Pokémon as he wished. Ash decides to lead off with Treecko against Pelipper.
Pelipper uses Wing Attack and Treecko dodges it, but 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 suddenly and suspiciously orders Pelipper to use Flamethrower, which hits Taillow and knocks it out, much to the shock of everybody, especially Max. Ash then uses Pikachu; when Pikachu uses Thunder, Pelipper is directed to counter with its own Thunder.
Meanwhile, Team Rocket plots to steal the Pelipper, and as they put their plan into motion, they manage to make a Bellsprout fall from Pelipper's mouth as Anthony tries to defend Pelipper with Water Gun, Flamethrower, and Thunderbolt at the same time. From this, they learn that Pelipper could perform the unusual attacks because its mouth houses a Bellsprout, a Magby, and a Magnemite. 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 by the world's most powerful Pokémon. However, Brock suggests that Anthony had 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, 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. As Team Rocket tries to escape with the stolen Poké Balls, they are attacked by Pelipper's Wing Attack, which frees their Poké Balls. When Team Rocket tries to take Pikachu as a last resort, Pelipper uses Water Gun to soak the balloon, allowing Pikachu to use Thunderbolt. The attack short-circuits Team Rocket's electricity-proof suits, sending them flying.
Anthony ultimately closes the Gym down and decides to use Pelipper fairly, as it was powerful even without the Poké Balls in its mouth.
During the fight between Pelipper and Pikachu, it was shown that Pelipper's mouth was heavy and filled with Poké Balls that Team Rocket had put in there for Meowth to choose the Pokémon. However, soon after Anthony's fraud is discovered, Pelipper's mouth seems back to normal.