The thing is, though, that actions speak louder than words. A pokemon may say it can't be evil, yet we see Arbok, an evolution of Ekans, in a later episode refuse an order from Jessie because he thought it was wrong. That alone should be enough to discredit what he said. Where one may see a pokemon being extremely obedient, I see the pokemon being a coward for not doing the right thing, or being outright evil. Butch and Cassidy's Drowzee was evil through and through and I hope it was killed in that explosion.
Team Rocket will pay for their crimes.