Try to Study! Pokémon Trainer's School! - S6-E15
Revealing mistake: When Ash says, "No problem!" in response to Roxanne asking if it is all right to postpone his match at the Rustboro Gym, Pikachu's mouth duplicates. Also, Ash and Roxanne go from being 90 centimetres from each other to being 30 centimetres away. Additionally, the former's bag goes from being present to vanishing. (00:06:18)
Try to Study! Pokémon Trainer's School! - S6-E15
Revealing mistake: When Anita says that Kenny does not care about Pokémon either, she is sitting in midair. (00:09:46)
Answer: He is a good guy but just found himself in a bad situation when he worked for Lysander. He didn't want him to harm Ash and his Pokémon when he was trying to get the special bond between Ash and his Greninja to work. He does leave Lysander and go back to being a good person.