Who Will Win?

The Ultimate Life Form vs The Ultimate Progenitor of Demons.

My Opinion: its a bit hard but, if both of they were at there prime then it could be an endless battle, since both of them are weakened to the sun, but since kars become one with the stone mask and the red stone of aja, i dont know how muzan could back up being immune to the sun. So maybe i go with Kars in this one.