There's a new Gym in Sinnoh, and Team Rocket is in charge! With Jessie as Princess Powerzone, the Gym Leader, and James as a crooked referee, there should be no way they can lose to their latest challenger—yet somehow they do. After the battle, Meowth goes out to get snacks and comes back home with an ominous Croagunk on its tail. Croagunk isn't impressed by Team Rocket, but they're impressed by Croagunk's Poison Jab move, so they recruit the Pokémon to help them out.
Elsewhere, our heroes encounter a Scizor and its Trainer, Minnie. Minnie is headed for the Powerzone Gym because she's heard that losing Pokémon can stay at the Gym to receive extra training. Minnie thinks it would be good for her Scizor, and Ash and his friends can't resist the chance to tag along. Ash wants to battle first, but Jessie wisely pretends not to hear him and chooses to battle Minnie instead.
James' creative refereeing gives Croagunk the victory over Minnie's Scizor, so Minnie lends Scizor to the Gym for training. Ash and Aipom are up next, but when Aipom wins, Jessie declares that Ash must battle her again—with Pikachu! That's the cue for Team Rocket to unmask themselves and their Pokémon-grabbing plan... which turns out to be no match for our heroes. Another Team Rocket scheme, foiled!
This still leaves the problem of all the Trainers who left their Pokémon with the Powerzone Gym. Minnie volunteers to watch over the Pokémon until their Trainers return, but Croagunk doesn't have a Trainer. So when Brock asks Croagunk if it wants to join him, it accepts. It's an easy catch, but it won't be that easy for Brock now that Croagunk is there to use Poison Jab every time he tries to swoon over a pretty girl!
A disguised Jessie uses her Dustox to battle a Trainer named Jeffrey and his Marowak. Jessie tells Dustox to use Stun Spore, but Marowak deflects it by spinning its bone. Marowak then uses Bonemerang, which Dustox dodges, but the bone hits Dustox on its way back. Marowak then finishes the battle with Bone Club. James, also in disguise, announces that Dustox is unable to battle, and tells Jeffrey to take a Badge from the stand next to him. Jeffrey and his Marowak then run out of the Gym excitedly.
Meanwhile, Meowth, who is also in disguise, walks out of a store and notices a wild Croagunk sitting nearby. Meowth then walks off, thinking that the Croagunk looks like a bully. Meowth is alarmed to discover that Croagunk is following him, and runs back to the Gym. At the Gym, James takes out his cards, and reads out a description of Croagunk, before they decide that he doesn't look very nice, so James tries to force Croagunk's face over his teeth, which causes him to use Poison Jab on him, making him fall to the ground. Jessie likes what she sees, and decides to use Croagunk in the Gym.
Ash, Dawn, and Brock are walking along a path, when a Scizor jumps out. Dawn scans it with her Pokédex, having not seen one before. Then its Trainer runs up, and Brock falls for her. The Trainer introduces herself as Minnie, and tells the group about a new Gym nearby, called "Powerzone Gym". The group decide to go there together.
While looking for the Gym, Minnie reveals that she is not a very good battler, and that the new Gym will train any Pokémon that loses to them. The group arrive outside Team Rocket's Gym, and when they enter they see Jessie and Croagunk battling an unnamed Trainer's Sandslash. Croagunk dodges repeated Slashes, and then dodges a Sand-Attack, before knocking out Sandslash with a Poison Jab. The Trainer runs over to check on his Sandslash, before handing its Poké Ball over to Team Rocket, with the belief that they will train it. Ash and Minnie then announce that they would like a battle as well. Team Rocket initially panics when they see Ash, but then decide that they haven't been recognized, and so should carry on with the plan. Jessie then introduces herself as "Princess Powerzone", and asks who wants do go first. Ash calls out that he will, but Jessie say that Minnie will, even though she didn't say anything.
Minnie and Jessie are ready to battle at opposite ends of the field, with James announcing the rules, while Ash and Brock explain Gyms to Dawn. Dawn asks to see the Badge, and Jessie and Meowth panic. James then shows them the Badge, which is obviously made of bottle caps. Minnie points this out, only to be shouted at by James. The battle will be 1 on 1. Jessie chooses Croagunk, who is already on the field anyway, and Minnie chooses Scizor. Brock shouts out his support (and love) for Minnie, but Jessie slaps him and tells him to be quiet. They then force James to decide on the winner of that "battle", and James, after considering who will hurt him more, chooses Jessie. The real battle then begins, with Jessie ordering a Poison Sting, which Scizor uses Quick Attack to dodge, before connecting with Slash and Metal Claw. Croagunk faints, but James delays for so long that Croagunk is able to climb to his feet and continue battling. Jessie commands another Poison Sting, but Croagunk hits Scizor with Brick Break, before using Poison Jab to knock out Scizor. This time James immediately calls Jessie the winner. Minnie hands over Scizor's Poké Ball for them to "train" it, but Jessie insists that she won't battle again till after lunch, so the group heads outside. Inside, Team Rocket start scheming.
Back in the Gym, Ash chooses Aipom for his battle, while Jessie, predictably, chooses Croagunk. Croagunk starts with Brick Break, but Aipom dodges and counters with a Swift, then follows with a Focus Punch. Croagunk hits Aipom with a Poison Jab, but when Jessie tries to use it a second time, Aipom uses Double Team to avoid it, and hits Croagunk with another Swift, followed by a Focus Punch, knocking Croagunk out. James cannot delay long enough for Croagunk to get back up.
Jessie then says that Ash must win another battle, and sends out her Dustox. Ash tries to send out Turtwig, but Jessie stops him, saying that in that battle she gets to choose his Pokémon. She chooses Pikachu, and when Pikachu runs onto the field to start the battle, a large rubber hand comes out of the ceiling and grabs Pikachu. Team Rocket's Meowth Balloon bursts out of the roof of the Gym, and Team rocket leap into it while saying their motto. The group all run after the balloon, which has Pikachu and the stolen Poké Balls in a net hanging beneath it. Croagunk has been left behind, which Brock notices as he runs after the balloon. Ash then releases Starly, telling him to use Quick Attack on the Balloon. Team Rocket laugh, as the first two attacks leave a mark on the balloon, but fail to pierce it. Their laughter stops however, when the third strike pokes a hole in their balloon. The balloon crashes, releasing Pikachu from the net.
Team Rocket jump towards Pikachu, with Meowth noting that they "still have 3 minutes left". Jessie sends out Dustox, but one Thunderbolt from Pikachu is enough to send them blasting off. The Poké Balls are left behind and Minnie recovers her Scizor from them. The group wonders how to get the Poké Balls back to their Trainers. Minnie says that she will wait at the Gym for the Trainers to come back for their Pokémon, as her battle made her realize that she still has a long way to go before becoming a good Trainer. Brock then states his love for her, but stops suddenly as he notices that Croagunk is behind him. The group say that they thought it was Team Rocket's, but Brock realizes that he was actually wild, and asks him if he wants to come along with him. Croagunk agrees, and Brock catches him in a Poké Ball. The group congratulate Brock, who then resumes stating his love for Minnie, before Croagunk pops out of his Poké Ball, and uses Poison Jab on him. The episode ends with Minnie and Scizor waving as Ash, Dawn and Croagunk walk off, with Croagunk dragging Brock behind him.