From Bulbapedia, the community-driven Pokémon encyclopedia.
The setting for the tournament
The Pokémon Ping Pong Tournament (Japanese: ポケモンピンポン大会) is an anime-exclusive event where Pokémon and Trainer form a pair and compete in a game of ping pong. The 32 Trainers use a paddle while the partner Pokémon uses its body to hit the ball. The prize for winning the competition are six golden ping pong balls and a runner-up reward is a year's supply of special Pokémon food.
The tournament was featured in To Thine Own Pokémon Be True! and held in Sandalstraw Town. Ash, Dawn, Barry, Jessie, Halverson, Wilkinson, and O competed in the tournament with Pikachu, Ambipom, Empoleon, Meowth, Marowak, Farfetch'd, and Shiftry respectively.
During Dawn and O's match, Dawn's paddle was broken, forcing Ambipom to continue alone. Though she fought hard, Ambipom eventually lost to O in the semi-finals, who later went on to win the tournament by defeating Theodore in the finals.
Known competitors's Pokémon
Other competitors' Pokémon