Mike. Kangaroos got big ass eyes that after three or four hooks would be swollen. Mike made a career of getting close so that kangaroo won’t be able to get any momentum behind them kicks.
I don't think animals swell up in the skull. I've seen dogs that were beaten in the face. They don't swell up like human. Maybe lack of muscle under the facial skin.
I shot a squirrel in the face with at 22 pellet rifle, it hurt him but he lived, his face wasn't all puffy and shyt.
That being said I think Mike can win, he just has to kill it. Most likely with multiple punches to ribs and bodily organs. The kangaroos claws would have to be taped up cause they kick you and disembowel you.