After traveling through many regions to perfect their fist techniques, Clayton and his Mr. Mime now live in an isolated area in Sinnoh, seeing it as suitable for their training. After witnessing Ash's Buizel's bravery, he asked it to a battle. Ash and Buizel accepted the challenge, but he and his Mr. Mime easily won. Afterwards, he taught Ash and Buizel on how to increase the speed and power of their punches, which, in Buizel's case, would lead to learning Ice Punch. After Ash and Buizel trained, Clayton was asked to have another battle. This time, Buizel was able to defeat his Mr. Mime with the help of the activation of Swift Swim and its newly learned move.
Clayton has a strange quirk in which he runs his words together, such as "Pokéner" (Pokémon Trainer), "battover" (battle is over), "unbegood" (unbelievably good), "nowo" (no worries), and "secplea" (seconds, please). He even dubbed Ash and his friends with abbreviated nicknames: Ash and his Pokémon as AshPika (Ash and Pikachu; Japanese: SatoPika) and AshBui (Ash and Buizel; Japanese: SatoBuoy), Dawn and her Piplup as "DawnPip" (Dawn and Piplup; Japanese: HikaPoca), and Brock as "BroBree" (Brock the Breeder; Japanese: TakeBree).
Mr. Mime is Clayton's only known Pokémon. It was easily able to defeat Ash's Buizel at first by stopping its moves with its Psychic powers, and later finishing it off with Thunder Punch. However, it was not the same in their second battle, as Buizel was able to use its new move, Ice Punch.