Crota is pretty tough. I mean, he might kneel down several times but so what? He'd get back up and use that fukin optimus prime sword to light the other dude up
Guys we killed crota in his weakest form. We had to take out his hands, eyes, heart, etc. we then had to kill all of his agents, and banish his soul. He was then able to appear on the moon, but not as a whole. Imo, if crota was at his fullest, he would -blam!- skolas
Crota, he's a God that can only be killed by an ethereal weapon in his own reality.
Skolas has been made my bitch in every environment I've met him, with whatever weapons we please
Realistically, Crota world win. Skolas is mortal. Crota is a Hive God. If Crota was ever summoned back to the physical world, another cataclysmic event would take place.
Look what happened to the Moon before.