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, Roderick was visiting Mirage Island when he stumbled across May and Drew. They had washed up on the island after getting caught by Team Rocket and getting mixed up in a whirlpool. Knowing the best way to reach Ash, Brock and Max would be by following the river, Roderick helped to guide the duo to that location. While leading them, he told them how he ended up on Mirage Island by accident many years earlier and that he was a Coordinator before. Once there, a group of Wynaut had rescued him, and guided him to several Liechi Berries.
When May and Drew fell into the river and Roderick couldn't rescue them, he found the rest of the group. Eventually, they found May and Drew and rescued them from Team Rocket. As Roderick drove the gang to their next location, he gave May several Liechi Berries to help her on her journey.
This listing is of Roderick's known Pokémon: