Plot hole: After Ritchie tells Misty that he never talked to them through a phone, Misty could have put two and two together and realised that Ash was told to go somewhere by someone impersonating Ritchie and that he might be in serious danger. However, she does absolutely nothing to help Ash, she doesn't even inform Brock about it.
Continuity mistake: When the phone rings, it is six centimetres away from the lamp, but in the next shot, it is fourteen centimetres away. Also, the cabinet is three centimetres away from the top of the planks directly above it, but in the next shot, it is six centimetres away. (00:04:34)
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.