I decided to put your fluffballs to the test. So far, my Mewtwo has done the following:
-lit it on fire
-beaten on it with weapons ranging from a platinum hammer to an adamantine two-handed sword
-beaten on it with its own vicious attacks (all of which are 10x larger and 100x faster than standard punches, kicks, etc.)
-inflicted it with the following syndromes:
--electricity (numbness, dizziness, pain)
--toxic poison (cough blood, necrosis, pain, drowsiness, dizziness, bruising)
--freeze (necrosis, paralysis, bleeding, severe speed drop)
--psychic damage (intense pain, severe dizziness, severe drowsiness, severe cough blood, severe bleeding)
-hit it with a telekinesis attack strong enough to send a full-grown dragon flying over 10 tiles away, repeatedly, smashing it against a wall
And the only way Mewtwo's killed one thus far is by throwing it into the waters of the arena and freezing it with Blizzard.
In short, I think you succeeded. Though there was one time where the game froze when Mewtwo landed an attack...
(The fluffball couldn't so much as touch Mewtwo, due to Mewtwo being immune to all of the fluffball's syndromes (Mewtwo's not in any poison class). Though, to be fair, it takes an army of about 30 dragons being spawned to completely surround Mewtwo on all sides to even damage it.)