They're also infinitely more powerful than your average human, though. You'd think that if a human treated their Pokemon poorly, the Pokemon would be able to retaliate before the human could get a handle on the situation. Admittedly, not all Pokemon are quite that powerful, but I wouldn't be surprised if there were a number of deaths at the fangs of a mistreated former Magikarp.

I think that basically any relationship you enter into has the chance of resulting in abuse or some sort of horrific agenda, so I don't really consider the Pokemon-Trainer relationship much different.