Ash, Dawn and Barry are all competitors in Sandalstraw Town's Pokemon ping-pong tournament, where Trainers form double teams with their Pokemon. Ash and Dawn warm up with a practice match, but Dawn's partner Ambipom smashes the ball so hard, it nearly hits a passing ping-pong player. As Barry later explains, that player is none other than O, the defending tournament champion! When practice is over and the tournament begins, Jessie and Meowth are among the competitors. But when Meowth gets carried away and uses a Pokemon move to slice the ball into bits, they're disqualified!
Ash ad Pikachu are taken out by an experienced Trainer and his Farfetch'd, but Dawn and Ambipom beat a Trainer and Alakazam to advance to the second round. Agile Ambipom can use its tails to return just about any shot, and as O watches from the sidelines, he can hardly believe Ambipom is new to the sport! Dawn and Ambipom defeat their next opponent and now it's Barry's turn to take on O. O and Shiftry make short work of Barry and Empoleon--that means O is Dawn's next opponent.
Though O quickly takes the lead against Dawn and Ambipom, Dawn is determined to fight back. But when she tries to return Shiftry's shot, it smashes her paddle into pieces! As Dawn helplessly watches, Ambipom takes over, using its tails to play O and Shiftry at the same time. Ambipom wins the second of their three matches and Dawn gets a replacement paddle for the third match, but O still wins and moves on to win the entire tournament. However, he's so impressed by Ambipom that he offers to take it on as a student.
Dawn doesn't know what to do, but she sees how much Ambipom enjoys ping-pong. So she leaves the decision to Ambipom: pursue Pokemon ping-pong or stay with Dawn and her Contests? Ambipom wants to play ping-pong, so it joins O and heads to O's training center in Kanto. Our heroes say a fond farewell to their old friend, who surely has a bright future in Pokemon sports!