Dawn, Ash, and Brock arrive in Chocovine Town to find everyone in a festive mood. It's not the upcoming Contest that has everyone excited—it's the annual visit of the Phione! These rare aquatic Pokémon can be seen near town and are said to bring good luck. That night, Dawn and her friends take a Phione-watching tour on a submarine, unaware that the submarine is crewed by Team Rocket. Three Phione swim past the submarine, and one of them is so interested in Dawn's Buneary that it stays behind after the other Phione have continued on their way. After the tour is over, Team Rocket returns and snags that lone Phione in a net, but makes the mistake of letting it out for a swim in the town fountain. Phione uses Acid Armor to escape down the drain so it can search for Buneary.
Phione finally catches up with Dawn and Buneary as they train near the beach. Team Rocket has been chasing their prize Pokémon all this time, and they show up to recapture Phione... but they're promptly ignored, for Phione has bigger things on its mind. As soon as it sees Buneary next to Pikachu, it challenges Pikachu as a rival for Buneary's affections! Buneary steps in and challenges Phione itself: if Phione wins, Buneary goes on a date with it! Captivated by the drama, Team Rocket temporarily abandons their plans and waits to see what will happen.
Soon after the battle starts, Phione and Buneary both use Ice Beam against each other, and neither Pokémon seems to have the advantage. However, Buneary uses this opportunity to strike while Phione is distracted, knocking Phione down for the count. Dejected, Phione bids Buneary farewell and turns to leave. When Team Rocket tries to grab it, Buneary and Phione use Ice Beam again, this time putting Team Rocket on ice so Pikachu can blast them into the sky. Phione is still broken-hearted, but Buneary promises they'll battle each other again some day. With its spirits buoyed, Phione happily swims away and rejoins its Phione friends!