It's a rough day for hero and villain alike, as Dawn's Piplup struggles to perfect a move for the upcoming Pokémon Contest and Team Rocket struggles to find something to eat. Team Rocket lucks out and finds a giant pile of berries in the middle of a field, but nearby footprints suggest the berries already belong to someone—or some Pokémon. Team Rocket steals the berries anyway, but a slip-up lands some of the berries in the possession of a Ludicolo trio. Then the berries' real owners, a Golduck and its Water Pokémon friends, show up and mistake the Ludicolo for the real berry thieves!
Team Rocket steps in and defeats Golduck, all part of their plan to get the Ludicolo on their good side so they can snag them for the boss. Alas, this plan is quickly abandoned when the grateful Ludicolo turn out to be too energetic for Team Rocket to bear. As for the dejected Golduck and its friends, they have the good fortune to run into Piplup. Piplup take charges and goes right up to the Ludicolo, determined to show them the error of their ways. Team Rocket watches it all while feasting on their ill-gotten berries and, unsurprisingly, decides this is a great opportunity to steal a whole lot of Pokémon at once.
Team Rocket pounces on the gathered Pokémon with the help of their Magikarp submarine. Piplup tries to save them, but Team Rocket launches a swarm of robot Remoraid that are just too much for Piplup to handle. That is, until Piplup finally pulls off a Contest-worthy spinning Bubble Beam move that wrecks the robots and turns the tide in our heroes' favor! Once it's revealed that Team Rocket had the berries all along, Golduck apologizes for falsely accusing the Ludicolo and the Pokémon join forces to beat Team Rocket. And with an amazing new move mastered, Dawn and Piplup can look forward to their upcoming Contest with newfound confidence!
Dawn rehearses her routine for the upcoming Jubilife Pokémon Contest. Dawn takes out her Poké Ball and summons Piplup. She orders a Bubble Beam. Piplup does so, creating a large ring of bubbles around itself while spinning to create a dazzling fireworks display. However, Piplup becomes dizzy from its routine, and eventually hits the ground head first. Despite the minor setback, Dawn bounces back and calls for another twirling Bubble Beam. But it the same result as before, with Dawn and her friends running for cover from the wayward attack.
Team Rocket, meanwhile, is lying on the ground out of sheet exhaustion and hunger. They soon get up, and all start looking around to see if they can see some food or something to steal. Out of nowhere, they come across a miraculously large pile of delicious looking Berries. Meowth prepares to take his first bite, but Jessie orders him to stop before pointing out a trail of nearby footprints. While Jessie is concerned about angering the Berry collector, she and her teammates put their stomachs first and run off with the load. The very Pokémon, a group of Water Pokémon led by a Golduck, who were stockpiling return to their pile with more Berries, but are frustrated to find everything gone. Meanwhile, Team Rocket are loading the berries into their docked Magikarp submarine. James accidentally drops one, so Meowth rushes to grab it. However, Meowth’s jump causes the loading plank to flip, sending the baskets of berries flying into the distance. Team Rocket soon tracks their stolen berries to a trio of dancing Ludicolo. Meowth smiles happily and remarks that the Ludicolo would make a great gift for Giovanni. Meowth’s boss fantasy is interrupted by the arrival of Golduck and its gang, who confront the Ludicolo over the berries.
As the rival Water Pokémon exchange words, Team Rocket settle on making off with both the Pokémon and the berries. Disguised in judicial wigs and gowns, Jessie announces that the court is in session. Golduck is first to complain, and points to the small pile of berries to accuse Ludicolo of theft. Jessie dismisses its point and requests hard evidence. Jessie announces that justice has been served, so she and her teammates prepare to walk away. However, Golduck is furious and insults the trio. Team Rocket responds by removing their disguises and calling out Seviper and Carnivine to handle it. While Carnivine chomps down on James's head out of affection, Seviper lashes Golduck with a Poison Tail. James orders Carnivine to use Bite attack, which is followed by Seviper using Haze to scare Golduck and its friends off. Team Rocket turn their attentions to the Ludicolo, who smile and greet the trio with open arms. The trio soon regrets their new alliance and flee, as the rather enthusiastic Ludicolo spin them around in happiness.
Elsewhere, Ash and his friends are sitting down to a delicious and relaxing lunch. Piplup decides now is a perfect time for practice, so it rushes into the high grass. Piplup jumps into the air and starts to practice its Bubble Beam appeal. Like last time however, Piplup becomes dizzy and hits the ground. By the time Piplup gets up, Quagsire and the other Pokémon in Golduck's group run past and smash into the small penguin Pokémon. Piplup isn't impressed, but Golduck starts to rant and rave. Piplup nods and motions to them to let it deal with their problem. Golduck is incredibly surprised at this, even more so when Piplup order them all to follow. Dawn and her friends are also astounded, so they decide to follow after Piplup and its marchers. Piplup confronts the Ludicolo with the allegations, though the Ludicolo will hear none of it and promptly spit out a triple Water Gun at Piplup’s face. In response to this, Piplup prepares to lash them with a Peck attack, only to be intercepted by a wall of sound. Piplup gets back up and puts its wing to its chest proudly.
From below the lake, Team Rocket watch the group. Jessie is thrilled, as they can grab Piplup too. Piplup tries another Peck attack, though the Ludicolo step aside to dodge. Unable to stop its momentum, Piplup flies into the distance and smacks into Team Rocket's periscope. James wonders what is blocking the lens, and spins the scope around to try to knock Piplup off. He fails, and Jessie takes over and manages to throw Piplup back into the lake. At this, Ash, Dawn and Brock run out from the high grass. Seeing this, the Magikarp submarine resurfaces from the lake, and Team Rocket emerges from inside and recites their motto. Piplup soon returns to shore, and determined to defend his pride, he jumps onto the submarine and starts to Peck at it. Piplup is thrown back into the lake however by the sub's tailfin, which prompts Ash to tell Pikachu to use Thunderbolt. Team Rocket quickly ducks back into the submarine and laugh as their Magikarp's electric-proof armor keeps them protected. Jessie tells Meowth to fire off the Magikarp's secret weapon. Two wires shoot out, ensnaring Golduck's group, the Ludicolo trio and Pikachu. Piplup swims back to shore and tries to free its captured friends, to no avail. Seeing that the wires are too tough to snap with its beak, Piplup jumps back at the submarine and starts to Peck it in anger.
Meowth presses a button, which fires several robotic Remoraid. The decoys batter Piplup from all angles, smashing into Piplup over and over again. Dawn, worried at her hurt Pokémon, runs towards Piplup through all the Remoraid. Piplup, seeing Dawn rush to his aid, twists into action with its Bubble Beam appeal. Piplup performs the technique and destroys all of the Remoraid bots, before making a perfect landing. Dawn is thrilled by Piplup’s progress, and orders him to lash Team Rocket's submarine with Bubble Beam. Piplup does so, and the spinning bubbles create a whirlpool which traps Team Rocket. The group release the captured Pokémon as Dawn hugs Piplup. The Magikarp sub bursts out of the lake again and Team Rocket gasp for air. Tired and hurt, Jessie, James and Meowth can't move quickly enough to dodge Pikachu's Thunderbolt which enters the insides and the resulting explosions sends them blasting off. The explosion also sends all of the stolen berries raining down on Ash’s group and the Pokémon. Golduck realizes that team Rocket were the real Berry thieves, and it promptly apologizes to the Ludicolo.
Later, Team Rocket crawl out of the water, but they are greeted by the angry gazes of the Ludicolo trio and Golduck's group. The three try to explain themselves and beg for forgiveness, but are quickly sent flying away by a group Water Gun attack. By evening, Ash, Dawn and Brock wave goodbye to the Water Pokémon and continue onto Jubilife City. Dawn order Piplup to try another Bubble Beam, and the successful practice leaves Dawn feeling confident for her upcoming Contest debut.