Stephanie's father is a character of the day who appeared in Having a Wailord of a Time. He is the father of the starting Trainer Stephanie. He accompanied his daughter to the Slateport City Pokémon Center so she could choose her first partner Pokémon. After his daughter chose Mudkip, the Treecko attracted his attention, and he asked Nurse Joy if he could have it as his own first partner Pokémon. Nurse Joy allowed him to be its Trainer, saying it was never too late to start. (Source: Bulbapedia)