From Bulbapedia, the community-driven Pokémon encyclopedia.
Roderick (Japanese: ロクスケ Rokusuke) is a character of the day who appeared in Who, What, When, Where, Wynaut?.
A former Coordinator with a bad reputation and the nickname "Roderick the Wrongdoer", Roderick had been stranded on Mirage Island forty years ago after being caught in a whirlpool. He was rescued by the resident Wynaut, all of whom he befriended after they guided him to several Liechi Berries. Even after he managed to escape Mirage Island, Roderick returned often to check up on the Wynaut. His encounter with them led him to become a kinder individual.
On one of his visits, he stumbled across May and Drew, who had washed up on the island after one of Team Rocket's schemes got them caught in another whirlpool. Knowing the best way to reach Ash, Brock, and Max would be by following the river, Roderick helped guide the duo to that location. While leading them, he recounted the story of how he first came across Mirage Island.
Eventually, May and Drew fell into the river, and Roderick couldn't rescue them. He found the rest of the group and guided them to May and Drew just in time to rescue them from Team Rocket. As Roderick drove the group to their next location, he also gave May several Liechi Berries to help her on her journey.
This listing is of Roderick's known Pokémon: