Thatcher
Thatcher is a character of the day who appeared in A Different Kind of Misty!. There he was taught to be a trainer by Ash, whom he thought was a legendary hero. He, along with his Pokémon, learned to battle bravely instead of cheering, which was all Plusle and Minun could do well at the time.
He reappeared in Cheer Pressure!, where he was training with a pep squad.