Who's That Pokémon? It's Seel!
Ash, Misty, and Brock are traveling to Cerulean City. Misty doesn't want to go to Cerulean, so she suggests going to Vermillion instead. Ash refuses and heads to the city to earn his Casadebadge. Meanwhile, Team Rocket is in Cerulean, stealing a giant vacuum and hose.
As Ash and Brock head to the city, they notice that Misty isn't following them anymore. Up ahead, they see a large group of people in front of a building. They manage to get in the front, and they see Officer Jenny. They ask her what is happening, and she says that someone stole a vacuum and a hose. Officer Jenny then accuses them of stealing the vacuum and hose. Ash shows Jenny his Pokédex, which explains that Ash is a trainer, and Brock shows Jenny the Boulderbadge and says that he was the former leader of Pewter City's gym. Jenny lets Ash and Brock leave.
After looking for the gym, Brock tells Ash that he has some things to do. He walks off, leaving Ash to find the gym himself. With a map and Pikachu by his side, he looks for the gym. After finding it, he walks inside, only to find a large crowd of people and three girls swimming in a pool. They are putting on a swimming show.
After the show ends, Ash walks around the gym and says that it looks like an aquarium. Suddenly he hears the three girls talking. He tells them that he is looking for the gym leader, and they said that he is looking at them. The three "sensational sisters", whose names are Daisy, Lily, and Violet, take Ash near the swimming pool.
Ash challenges the sisters to a battle, but they refuse. One of them explains that their Pokémon had to be taken to the Pokémon Center, because they were beaten by kids from Pallet Town. The three sisters show Ash their Goldeen, who only knows Horn Atack. One of them calls for a Seel, who gives her a Casadebadge. They tell Ash that he can have the badge, but he says that he'd like to earn his badges.
Suddenly a voice challenges Ash to a battle. Ash turns around to see Misty. Daisy, Lily, and Violet are rather surprised to see Misty. Ash soons finds out that Misty is the fourth sensational sister. After a bit of teasing from her sisters, Misty and Ash decide to battle.
Ash starts off the battle by sending out Butterfree. Misty responds by sending out Staryu. Ash tells Butterfree to use its Stun Spore. Misty's Staryu manages to wash off the spores. Butterfree uses Sleep Powder, but Staryu goes underwater. While Butterfree is in the air, Staryu does a surprise underwater tackle, knocking an angry Butterfree into the water. Ash recalls Butterfree and sends out Pidgeotto. Misty recalls Staryu and sends out Starmie. Pidgeotto uses Whirlwind and then Gust, knocking Starmie into the gym wall.
The wall suddenly breaks open, and Team Rocket comes with a giant vacuum and hose. After reciting their motto, they begin to suck the pool dry. Daisy, Lily, and Violet's Seel gets sucked into the pool, and Ash's Pikachu falls in as well. Pikachu gives a Thundershock to Team Rocket's hose, which turns it into reverse. Team Rocket gets sucked up into their own machine. As Seel (who has safely landed outside) claps for them, Team Rocket blasts off again!
After the ordeal with Team Rocket, Daisy, Lily, and Violet give Ash the Casadebadge for saving their gym. Misty complains and says that he doesn't deserve it. Brock comes back and Ash holds up his new badge. The three of them then leave the city, with Misty complaining about their battle...