The Pi-Kahuna

Plot
Ash and his friends, training for the Pokémon League, are jogging on one of Seafoam Islands' cliff-side roads. Ash, wearing his white-and-orange shirt, is ahead of Misty, who is wearing a blue outfit, and Brock, who is in his basketball jersey. However, Ash's progress is interrupted when a truck passes by, blinding him with its exhaust. Because of this, Ash does not see another vehicle heading in his direction, but it manages to swerve out of the way, leaving Ash unharmed, though it creates a large pileup behind him. Officer Jenny arrives to defuse the arguments between Ash and the drivers, who quickly speed off. As Ash wonders why the road would be so crowded, Officer Jenny tells them that it is the surfing season, and that the famous wave Humungadunga is coming. Surfers from all over the world have tried to ride the Humungadunga, which only appears once every 20 years, and plant their flag at the top of a rock, much like a famous surfer named Jan had done some 40 years ago.

Ash decides to also try surfing out, but his first try does not bode well. He tries again, but his foot cramps up. At that moment, he is saved by an older man and his Pikachu whose tail glows before a wave arrives. As Ash recovers in a seaside cabin, Misty and Brock introduce him to Victor, the cabin's owner, and his Pikachu, Puka, who saved him from drowning. As Pikachu meets Puka outside and watch the sea together, Team Rocket, in the Gyarados submarine, plots to steal them both.

Meanwhile, Victor reveals his past: 40 years ago, he had been a young surfer who tried to emulate Jan. Although he was not that good, Jan eventually took him under his wing, teaching him all about surfing. After Jan conquered Humungadunga and planted his flag atop the rock, he gave his own surfboard to Victor, as well as a word of encouragement. With that, Jan had left to see the world. 20 years later, the Humungadunga had arrived, but Victor had failed to conquer it. Discouraged, he was about to give up on surfing, but he then met Puka, who had been cast away on a tiny raft. Since then, the two have worked as a team: Puka had the ability to sense the waves, emitting a bluish glow whenever a big wave approached, and it helped the two conquer many big waves on the island, with Humungadunga being the only one that they have yet to conquer.

Just then, Team Rocket kidnaps both Pikachu and Puka, sealing both in a glass container. Diving down to make their getaway, Team Rocket encounters a group of real Gyarados during their mating season. They attack the submarine and finish it off with a Hyper Beam, causing the now-destroyed submarine to launch into the air. This sends Team Rocket blasting off, and frees Pikachu and Puka. Chasing after them on a boat, Ash has Bulbasaur catch Pikachu, but Puka falls into the water. Victor dives into the water and rescues Puka using Jan's surfboard. However, the waves become more fierce and Brock, now driving the boat, is forced to retreat before they capsize. Now alone in the water, Victor notices Puka beginning to glow, a sign that Humungadunga is coming.

Ash and his friends are warned by Officer Jenny to evacuate the beach and stand as far back as possible. Worried about Victor and Puka's safety, they are relieved when to see them riding the wave from atop a nearby cliff. They manage to position themselves close to the rock and plant their flag atop it, next to Jan's. Back on shore, Ash congratulates Victor for achieving his lifelong goal. He then turns to a small group of young surfers, and reiterates Jan's advice from 40 years before in an attempt to inspire the next generation of surfers.

Meanwhile, night falls, and Team Rocket is seen atop a rock with half of their submarine as several Gyarados swim around them.