James and Meowth proclaim that it is a great day to steal Pikachu. Jessie, however, just wants to relax as she lies on a lounge chair in the shade of a beach umbrella. They begin to complain, but she continues to relax, taking a sip of her tropical beverage. Tensions escalate as Wobbuffet stretches out on another chair. While they fight, a strange creature speeds towards the beach from the ocean. Jessie notices it and screams. The mysterious creature rams them from under the sand, sending the trio flying. It then burrows into the ground and away from the scene.
As the morning sun radiates over Dewford Island, Ash declares it is a perfect day for a lot of training in preparation for his rematch against Brawly. As Lotad waddles up with some water, he and Pikachu begin to wash their faces. May and Max sit at a nearby table brushing their teeth while Brock and Torchic start a fire to prepare a stew. Ash releases his Taillow and Treecko, and they--along with Pikachu--begin to meditate on the shoreline. Ash starts to explain to his Pokémon the importance of meditating, and for them to think about winning their upcoming rematch. Max sits at the edge of a pool of water washing clothes, and Forretress collects and dries the clothes with its Rapid Spin attack. Max thanks it before bringing the washing over to May to hang on the line. May is curious about Ash's meditation, and Brock informs her that meditating is actually a form of training, as it improves the patience of Ash and his Pokémon for their battles.
A large wave approaches the shore. Taillow begins to freak out, but Ash tells it to keep meditating, because if it can learn how to sense the waves, they may be able to beat Brawly and his surfing techniques. Taillow shuts its eyes and continues to meditate as Ash listens intently. As wave grows larger and nearer, Ash orders them all to get out of the way. However, the wave proves too quick, leaving Ash and his Pokémon soaked. May and Max complain about Ash's training and that they're stuck doing all the laundry. Brock replies that training isn't always about Pokémon. Ash and his Pokémon return to their practice. This time they all get up in time, except for Treecko who doesn't open its eyes in time. Ash cannot understand why Treecko didn't move, but he swipes back at May's comment and suggests she try practicing for her Pokémon Contests. Max turns to his sister and asks if she is ready. As Brock brings the group some tea, May leaps up and says she has been practicing her entrance. She then spins around and sends out Torchic and Wurmple. The two begin to play around, but May comments that they have to learn to be more graceful, and she recites her dance routine. Max points out that Coordinators can't let out two Pokémon at the same time in Pokémon Contests, and Brock adds it will not be a good idea for May to dance around like that, since in Pokémon Contests the focus is always placed on the Pokémon. May admits that she wasn't aware of the rules and was focused on her choreography, which she based on Steven's smooth battle style.
Suddenly, they all notice that the tent is walking away. The group gives chase and Ash orders Pikachu to shock it, but Brock stops him and explains that an Electric attack might set the tent ablaze. The menace soon crashes into a tree and it begins to flee underground. May tells Wurmple to stop it with String Shot, but as it tries to reel it in, Wumple is pulled along. Treecko grabs on to help, but it is also dragged forward. Ash and the others all grab the thread and start to heave, but the creature drags them along the beach. It soon retreats to the water, causing everyone to fall in. Once everyone's clothes are hung up to dry, Ash stands on the beach covered in sand. They inspect the damaged tent and the ruined rice balls that litter the beach, wondering what could have done such a thing. The group considers that Diglett or an Aron might be the culprit. Brock begins to sew the tent up while exclaiming that a Pokémon that could pull all of them like that must be really strong, but May just thinks it was scary. Ash declares that he wants to catch it. Brock and Max agree to help, but May just sighs.
Meanwhile, up on a cliff, Team Rocket is recovering from their earlier blastoff. Jessie remarks that the menace hasn't seen the last of Team Rocket. Wobbuffet pops out at the edge of the cliff and Jessie turns to recall it in exasperation. She then notices the mysterious creature speeding up the beach under the sand, and she points it out to her teammates. Jessie sets off on foot to get her revenge, but accidentally steps on a sleeping Loudred. Jessie steps back and freaks out as the Pokémon angrily wakes up. It lets out a cry which sends Team Rocket sky high.
That night, Ash and friends sit by some bushes and wait for the mysterious creature to take their bait. May complains that she is tired and wants to go to bed, but Ash refuses to sleep. Max angers May with a smart-mouthed comment and she begins to hug him tightly because she is scared. Pikachu then hears something and Ash asks if the creature is close. As they wait, Ash suddenly hears something behind him, but it is too late. The creature smashes into them, sending them all flying onto the beach. It continues its pursuit, prompting the group to split up. It sets its sights on May as she runs screaming in fear. Ash turns around and tells Pikachu to Thunderbolt it. The attack hits, but the menace quickly disappears underground and without a trace.
The following morning, the group is slumped against the tent in exhaustion. May cries out that they should not waste their time catching it and demands they move to another camping spot. However the others disagree, keen to find out what the mysterious creature is. Ash adds that he saw a red "horn" protrude from the sand after it was hit by Pikachu's earlier attack. He quotes one of Professor Oak's poems, admitting that the culprit is likely to return once again. The group then heads back to the beach and Brock has Forretress make several huge holes in the sand with Rapid Spin. Ash explains that they are going to use create pitfall traps, and the tactic instantly reminds May and Max of Team Rocket’s classic trick. Everyone proceeds to cover over the holes with leaves and sand.
That night, the group waits in the bushes again while watching the Pokémon food. Ash alerts everyone as four large bunches of seaweed emerge from the water. They walk up and begin to eat the Pokémon food. Brock says the plan is working and he sets some more food on a nearby rock. One of the seaweed bunches spies this and they head towards the new food, only to fall into a hole. The group approaches, only to discover that they have snagged Team Rocket. As Jessie and James begin their motto, May and Max interrupt, asking why they were covered and seaweed and eating Pokémon food. Team Rocket cowers in the hole, saying they had to make do. Suddenly, the creature emerges from the hole and smashes into Team Rocket, sending them blasting off again. The creature slides up the side of the pitfall and heads towards the bait, but Pikachu uses Quick Attack, sending it flying out of the sand. It lands with a thud and is revealed to be a Corphish.
Ash scans it with the Pokédex, and Brock adds its territorial behavior is a classic trait of Corphish. Ash reiterates his desire to catch Corphish, fully aware of its incredible speed and power. He sends in Pikachu as Corphish gets up. Max thinks the battle will be easy for Ash, as Corphish is at a disadvantage due to being a Water type. Pikachu starts with Thunderbolt, but Corphish dodges and uses Bubble Beam. It then burrows into the sand, leaving Pikachu confused. Corphish soon emerges, sending Pikachu flying into the air. As he descends, Pikachu tries to use Iron Tail, but Corphish catches him with its pincers and chucks him at Ash. Brock remarks that this Corphish is stronger than anticipated, and that Ash has a challenge on his hands. Ash agrees and calls on Treecko for assistance. Ash tells Treecko to meditate, and it closes its eyes and stands there. Max and May are astounded by the tactic, but Brock reassures them that Ash has a plan. The sun begins to rise and Corphish becomes impatient. It uses Bubble Beam, but Ash tells Treecko to hit them away. It uses Pound to break through the attack. Corphish begins to steam and rushes in for a Crabhammer, but Treecko lashes it with a Quick Attack, sending the Corphish flying. Treecko follows up with Pound and Corphish lands on the ground. Ash instantly throws a Poké Ball, officially catching Corphish. Brock commends Ash on his strategy of using Corphish's own impatience against it, while Max adds that at least Ash has learned from his earlier Dewford Gym loss. Ash calls Corphish out and kneels down to introduce himself. Corphish smiles and shakes his hand, but ends up tossing Ash in the process. Everyone laughs at Corphish's overwhelming strength before going over to check if Ash is okay.