It's a matter of her being able to use the abilities of other monsters I'm more concerned about. I would prefer to keep it in a way that doesn't cheapen were monsters and or null other monsters.

You can transform into basic animals (falcons, bears, bugs, fish, etc) and gain their abilities but not other monsters. Thus say werebears and the like don't lose their uniqueness that is exclusive to them. Granted normal bears are more than powerful enough.