From Bulbapedia, the community-driven Pokémon encyclopedia.
Ash and Gary during the race
The Extreme Pokémon Race is a popular sport in Eggseter, a town in northern Johto. It is a race where the competitors put their Pokémon in a leash and collar and have them pull them on a skateboard while carrying around a Toy Pokémon Egg. The prize is a Golden Poké Ball trophy for the Trainer and a medal for the winning Pokémon. Ash and Gary competed with each other in the race in Extreme Pokémon!, with Ash ultimately winning by using his Bayleef.
Pokémon entered in the tournament