>>44072464First of all, we can see that Lopunny's eyes are only the red part on the official textures for ORAS/USUM. If you look closely, you'll notice that Mega Lopunny has even more black around its eyes compared to Lopunny so either its eyes change shape completely or the black part is just furless skin.
We also have the fact that Mega Lopunny has black fingers and a black neck on top of the black "ripped thights." All of these parts are the same color, so they must be its skin.
We also have the Ultra Moon Pokédex entry:
>Mega Evolution awakens its combative instincts. It has shed any fur that got in the way of its attacks. 
