• English / United States: Clayton's Mr. Mime
• Japanese / Japan: キジュウロウのバリヤード
• Japanese (Romanized) / Japan: Kijūrō no Barrierd
• Japanese (Trans) / Japan: Kijuro's Barrierd

Clayton's Mr. Mime is Clayton's partner, who has trained with him for many years. They have even traveled together through many regions in order to improve their skills, but have lately settled in a forest near Daybreak Town, which they use as a field to eagerly train against other Pokémon and achieve even higher goals.

Clayton used his Mr. Mime against Ash's Buizel both in their first and in their rematch battle. In the first battle, Clayton's Mr. Mime proved to be stronger than Ash's Buizel, and managed to dodge its opponent's Aqua Jet and SonicBoom attacks by skillfully using its Psychic and Double Team moves. It then knocked Buizel out with a powerful ThunderPunch. In the second battle, however, Buizel turned out to be more of a challenge for its opponent Mr. Mime, as it had mastered a new move; Ice Punch. After activating its ability, Swift Swim, in the midst of the battle due to a sudden rain, Buizel managed to increase its speed and finish Clayton's Mr. Mime off with a powerful Ice Punch.

Mr. Mime appears to share a really strong bond with its trainer, Clayton. Both it and Clayton also really enjoyed Brock's meal, which he prepared after Clayton's first battle with Ash Ketchum.