Though Misty attempts to stop Ash from going to Cerulean City, Ash still goes to the Gym and encounters the Cerulean City's Gym Leader sisters. As they are about to give him the badge (as their Pokémon have been exhausted from the battles of previous Trainers), Misty appears to give Ash the challenge, even if she left the Gym to become a better Trainer. Will Ash be able to defeat her?
At the start of the episode, Misty tries to convince Ash and Brock to bypass Cerulean City and go straight to Vermilion City. She fails and says that she will wait for Ash and Brock outside of town.
Later, Team Rocket enters a building looking for something to steal Pokémon with and they find what they're looking for.
The next day Ash and Brock enter the city, then they notice that Misty is gone and Ash doesn't mind it though Pikachu misses her. Later that day, they see a crowd of people around a building and wonder what's going on. They head over and see Officer Jenny standing at a crime scene. Officer Jenny accused them of being the thieves that stole a giant vacuum machine. Ash and Brock prove to Officer Jenny that they are innocent, she lets them go. After that Brock asks Officer Jenny out on a date but she turns him down. She then tells Ash what the thieves stole and tells Ash and Brock to move along.
Ash asks Brock if he can tell him anything about the Cerulean City Gym Leader. Brock says that since he is also a Gym Leader, he can't tell. Brock says that he has something that he needs to do and Ash heads to the Gym by himself.
When Ash arrives at the Gym, he sees three sisters performing a show. Ash confronts them backstage and discovers that they are the Gym Leaders and he challenges them to a gym battle. The girls (Lily, Daisy, and Violet) tell Ash that they can't because their Pokémon have battle three other Trainers from a place called Pallet Town and their Pokémon are all worn out. The only Pokémon they have left is a Goldeen that only knows Horn Attack. They offer Ash a badge without battling when Misty appears saying that she, the fourth Cerulean Sister, will battle him.
It turns out that Misty is the youngest Cerulean Sister but the other three call her a runt. After Misty fights with her sisters, Misty challenges Ash to an official 2 on 2 gym battle. Ash accepts.
At the start of the battle, Ash tried to send out Pikachu, but Pikachu didn't want to battle Misty. Ash then sends out Butterfree instead. While Misty sends out Staryu. Even though both sides are even, Staryu quickly knocks Butterfree into the water, making it lose. Misty withdraws Staryu and sends out her Starmie and Ash withdraws Butterfree and sends out his Pidgeotto. Pidgeotto uses Whirlwind on Starmie, but it jumps into the water and Tackles Pidgeotto. Pidgeotto use Wing Attack, but got hit by Starmie's Tackle again. Pidgeotto used Gust on it, making Starmie hit the wall.
Just as Ash is about to win, Team Rocket bursts in with the stolen vacuum and tries to steal all the water Pokémon with it. Their plan is to steal the water from the pool. It sucks in all the Pokémon including Seel and Pikachu but Ash tells Pikachu to use Thunderbolt due to water conducting electricity. The attack causes the machine to malfunction and Team Rocket to get electrocuted and fall into the water. They are then sucked down into the vacuum and, to the delight of Seel, blasted out from the other side and fly off into the sky.
After Team Rocket goes flying, Daisy gives Ash the Cascade Badge. Misty protests this until Daisy points out that if Ash used Pikachu from the start he would have won. Ash gladly accepts the badge. Ash and Misty leave the gym while arguing, meeting up with Brock and they all head out to Vermilion City.
"Very scary ghost Pokémon that look like this. Like monsters." - Misty
"(laughter), Nice face Misty. Come on Brock, Let's go Pikachu." - Ash after a slight pause
"Hey wait hey wait a second! Hey what about Vermilion City? It's right on the water and there are lots of neat Pokémon, and you can watch all the giant yachts pulling into the harbor. And there's a little park way up on a hill where you can sit and watch the sunset that's so romantic." - Misty
"Uh huh." - Ash
"It's much nicer than that old Cerulean City so let's get going." - Misty
"Ok, let's go." - Ash
"Really?" - Misty
"To Cerulean City." - Ash
"Um, miss. I was wondering, since I'm new in town maybe we could get together tonight and you could show me around." - Brock
"Well I'm not off duty till past your bedtime, and I may even have to work 'round the clock to catch these burglars." - Officer Jenny
"" (parodying "Agarime Sagarime") It was just one defeat after another my eyes were spinning from all the losses."" - Violet
"I'm the fourth sensational sister!" - Misty
"There are only three sensational sisters and one runt." - Lily
(Misty glares angrily at Lily)
"Well then I guess like you came back because you couldn't make it as a Pokémon Trainer." - Daisy
"It wasn't my idea to come back here. The only reason I'm here is because he wanted to come." - Misty
"Well he's totally not someone I'd choose for a boyfriend but you're no prize yourself." - Daisy
"My boyfriend! If I battle him that'll prove I'm not a quitter and I'm just a good a Trainer as you three." - Misty
"Well, you are the only one of us with the Pokémon that can actually battle." - Daisy
"All right Ash, are you ready to rumble?" - Misty
"Leave it to a girl to show off her jewelry." - Ash
"Quit stalling and let's get this show on the road!" - Misty
"Oh no, Staryu looks like it's in real pain." - Misty
"It doesn't even have a face. How can you tell?" - Ash
"Because I'm sensitive to others feelings, that's how." - Misty
"Oh yeah , like I'm not?" - Ash
"We've gotta protect the Pokémon." - Misty
"Like what about my hair?" - Violet
"Now I know how it feels to be all washed up." - James
"We'll never come clean." - Jessie
"I wanted to win." - Misty
"I guess I'm not gonna get that Cascade Badge." - Ash
"Wrong. We're giving this badge to you." - Daisy
"Huh?" - Ash
"How come he gets the badge? He didn't win." - Misty
"Pikachu was the one that like totally saved us all, and if he had used Pikachu from the start, there was no way your Water Pokémon could've won." - Daisy
"Aww man." - Misty
"Misty, you just go right on trying to be a Pokémon Trainer. You might as well be good at something, cause you'll never be stars like us." - Lily
"You keep that up and you'll be seeing stars!" - Misty
"Chill out." - Violet
"Misty, be careful. You know we love you." - Daisy
"Yeah." - Misty
"You're not leaving without me." - Misty
"Misty, you're not gonna be a sore loser are you?" - Ash
"I didn't lose anything! It was a draw!" - Misty
"Well I'm the one who got the badge!" - Ash
"What? You know you lost with Butterfree!" - Misty
"That was just round one! I made a great comeback!" - Ash
"If Team Rocket hadn't busted in I would've destroyed you!" - Misty
"You're lucky they showed up! You were about to lose!" - Ash
"Lose? I was just getting started!" - Misty
"Oh yeah?" - Ash
"Oh yeah!" - Misty
"Oh brother." - Brock
"And we had to like rush all of our Pokémon to the Pokémon center." - Daisy
"(pulls out poke ball) This is the only one we have left." - Lily
This episode marks the first time Brock asked out a girl, which he does many times throughout the anime.
This is the first time Pikachu does not participate in Ash's Gym Battle.
This is the first time non-Pokémon creatures are seen.
In the Spanish dub, Misty's sister calls for Seel, but mispronounced it as See-al instead of Seel.
In one point, Ash's Pikachu's part of its right ear is missing.
The star that's usually seen when Team Rocket blasts off did not make a sound in this episode.
When Team Rocket arrived, Ash's hat was discolored.
At the end of the recap in the English version, the Cerulean City sign post is still written in Japanese even though it was translated into English in the previous episode.
At two points when Team Rocket arrive at the gym, the peak of Ash's cap is white.
In the English dub, during the opening and right before the title appears, the text on the sign Gary wrote on is in Japanese although the dub is in English.
While there wasn't a clear winner after Team Rocket interrupted the battle between Ash and Misty, the original has Violet saying that their match went down the drain, and Lilly saying that it was a Water-Draw, while the dub has Violet saying that the match was postponed.
Misty is shocked to find out they're heading to Cerulean City