From Bulbapedia, the community-driven Pokémon encyclopedia.
Theodore is a character of the day in To Thine Own Pokémon Be True!. He made it to the finals of the Pokémon Ping Pong Tournament with his Gliscor and lost against O and his Shiftry. He did not have a speaking role in the episode and was unnamed in the Japanese version. He never appeared in person, but his face appeared on the screen showing the finalists.
This listing is of Theodore's known Pokémon: