>>3993124
Charizard never seriously injured Ash. He just singed him. And that's a particularly ornery pokemon. Most aren't even that mean.
And yes, villains try to steal pokemon. But, with few exceptions, they can't actually use them for battle unless they can convince them to fight willingly. Pokemon can canonically leave their pokeballs on their own and run off if they hate their trainers. Which they would do if their trainer was a serial killer.