From Bulbapedia, the community-driven Pokémon encyclopedia.
Sullivan (Japanese: スズムラ Suzumura) is a character of the day who appeared in Whiscash and Ash.
A self-proclaimed "fishing god", Sullivan's ultimate goal is to capture a Whiscash nicknamed Nero. He has an extensive collection of fishing lures and rods. For 50 years, Sullivan tried countless times to catch the Pokémon, but he always failed. He hoped that, with the help of Ash and his friends, he would finally achieve his goal. Ash wanted to catch Nero as well since the Pokémon had eaten his Badge case.
Even though Sullivan described himself as a fishing legend, Ash caught Nero on a fishing rod, forced it onto land, and weakened it with Grovyle's Pound. After a foiled attempt at capturing Nero by Team Rocket, Sullivan sent out his Flaaffy, nicknamed Hannah, to battle Nero and decided to use his secret weapon: a Master Ball. He threw it, but the Water/Ground Pokémon opened its mouth and ate the Ball.
Though he was stunned by this, Sullivan remained optimistic, vowing to never give up on trying to catch Nero, claiming that the hunt would always be exciting for him. Wishing Ash luck on his next Gym battle, he said the group was welcome to stop by whenever they felt like fishing.
- Sullivan's outfit has a symbol of a Whiscash on the back.