From Bulbapedia, the community-driven Pokémon encyclopedia.
Stefano (Japanese: シゲキ Shigeki) is a character of the day who appeared in Disguise Da Limit. He is a Pokémon Coordinator who entered the Verdanturf Town Pokémon Contest with his Wartortle in hopes of winning the prestigious Verdanturf Ribbon.
Although his performance in the first round was not shown, it was deemed impressive enough by the panel of judges and put him in the Battle Stage of the Verdanturf Contest together with May, Timmy, and Jesslana. There, he and his Wartortle were matched up against May and her Skitty. However, Wartortle ended up being defeated with relative ease. As a result, Stefano was eliminated from the competition.
This listing is of Stefano's known Pokémon in the anime: