From Bulbapedia, the community-driven Pokémon encyclopedia.
Rikishii Town (Japanese: リキシータウン Rixie Town) is an anime-exclusive location. It is located in between Ecruteak City and Olivine City. It was featured in Ring Masters.
The town's main attraction is a Sumo Conference involving Pokémon facing off against each other. Ash entered the competition against the current champion Raiden and his Feraligatr. He entered his Snorlax into the competition. It defeated Raiden, and Ash received a King's Rock for his victory.