Bulbasaur and the Hidden Village - S1-E10
Continuity mistake: When Ash takes out his Pokédex to find facts about Oddish, the end of his right thumb is not over the center part of it, but in the next shot, it is. (00:02:14)
Bulbasaur and the Hidden Village - S1-E10
Continuity mistake: When the camera begins panning up to Ash and Brock tending to a Staryu, a saucepan appears from nowhere. (00:10:28)
Bulbasaur and the Hidden Village - S1-E10
Other mistake: In the scene when Team Rocket tries to steal the Pokemon, Bulbasaur saves Oddish. Ash comes to help push Bulbasaur, and for a few frames you can see 2 sets of hand prints cut out where Ash's hands go.
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.