Ash and his friends first met him after walking through Rikishii Town and noticing Raiden and his Feraligatr training at a local facility. His knowledge and passion for the sport inspired Ash to compete. He watched over the entire tournament, and used his high-ranking position to protest the referee's ruling that "Jessiyaki" and her Wobbuffet, disguised as a Miltank, won against an Ursaring. Team Rocket's cover was blown after Shonosuke disqualified them for using the move Counter. After their defeat, the tournament continued on, and he later presented Ash with the Sumo Conference title and winning prizes.
Shonosuke's name comes from the famous Japanese sumo wrestler Shonosuke Kimura.