The Pi-Kahuna is the 67th episode of the Indigo League season.
Whilst Ash and Pikachu are running alongside the highway at Seafoam Island, he is blinded by the smoke and mud released by a car. He ends up walking into the middle of traffic, causing a major blockage on the road. Officer Jenny arrives on motorbike to absolve the situation. As Jenny directs the cars through one by one, she reveals that there were so many cars due to a legendary wave called Humunga Dunga, which hits Seafoam Island once every two decades. Jenny retells the story of a prodigous surfer named Jan who rode Humunga Dunga and planted a flag on top of a nearby rock. Ash uses the recent conversation as an excuse to go surfing.
Pikachu becomes aware of another Pikachu sitting on a rock cliff, who becomes aware of a huge wave approaching. Ash fails to properly surf across a wave, crashing onto his surfboard, just as an even bigger wave towers above him. He is knocked unconscious by the force of the wave, but is rescued by the Pikachu and its owner. Ash regains consciousness back at the surfer's shack, who introduces himself as Victor. Victor tells Ash to thank his Pikachu, Puka, for rescuing him. Meanwhile, Team Rocket watches Ash's Pikachu and Puka sitting on the cliff face from inside their Mecha Gyarados. Victor tells Ash the story of how he and Puka met, in which it was lost at sea.
He explains that Puka is unusual as it can sense the motion of the sea, and as a result can discern when a big wave is coming. Victor says that Jan was the reason why he took up surfing, and thought he could sense waves like Puka. When Jan rode Humunga Dunga and planted the flag on the rock, he gave his surfboard to Victor and left Seafoam Island to travel the world. When he attempted to scale Humunga Dunga like Jan, he failed and resolved to give up on surfing. However, he found Puka. Victor explains that with Puka's help he has traversed every kind of wave, with only one exception. They are interrupted by Puka and Pikachu's cries, as Team Rocket attempts to steal them with their Mecha Gyarados.
As Team Rocket descend into the ocean, they encounter a swarm of angry Gyarados, who proceed to attack their ship with Hyper Beam. Ash, Brock, Misty and Victor search for them via boat, as Misty notices the Mecha Gyarados emerging from the ocean. It is destroyed upon its entrance, as Pikachu and Puka are both sent hurtling into the air. Ash uses his Bulbasaur's Vine Whip to rescue the two Pikachu, as Team Rocket blast off once again. However, Puka is unable to grab hold of the vine, as Victor leaves to rescue his Pokémon. Ash, Brock and Misty are sent rushing through the water by strong currents. As Victor reaches Puka, it senses the presence of an extremely large wave, which Victor deduces to be Humunga Dunga.
Officer Jenny orders for the beachgoers to evacuate immediately, the civilians eagerly looking on from high ground as the spectacle unfolds. Ash watches with awe as Victor and Puka emerge above Humunga Dunga, scaling the huge wave. Victor unveils his own flag, and manages to thrust it into the rock right next to Jan's flag. The crowd applauds his exceptional feat, as Ash exclaims that Jan would be proud of him. Seeing two budding surfers in the crowd, he walks over to them and says that one day they too will scale Humunga Dunga. Meanwhile, Team Rocket sit patiently inside the remains of their submersible, surrounded by a group of Gyarados, waiting for the next Humunga Dunga.
- Ash's Pikachu's tail is applied the incorrect colour scheme when the two are jogging beside the highway; in which it has a yellow base and a brown tail, rather than it being the other way around.
- The title of this episode is a reference to The Big Kahuna.
- "Hey, you can do it too"
Jan after surfing the Humunga Dunga and giving his surfboard to Victor.