I don't know why Jessie, James and Meowth still work for Giovanni. In my opinion, they are good guys. On a few occasions, they have saved Pikachu, Ash and his friends.
Jessie, James and Meowth are not evil. They don't do anything to hurt other people. All they want is to capture Pikachu. I think other villans in the anime are really evil.
When do you think they will turn good and work with Ash?
Do you think we have to wait for them to turn good until Ash becomes a Pokemon Master?