Clefairy and the Moon Stone - S1-E6
Continuity mistake: When Zubat is hit by Koffing, the back of its wings changes from blue to purple. (00:08:36)
Clefairy and the Moon Stone - S1-E6
Other mistake: When the camera begins panning back to show Seymour, Ash, Butterfree, Zubat, and Brock, Pikachu's mouth is missing. (00:11:18)
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.