Vitali would batter Velasquez in one quick round. And if any MMA fan tries to claim Edgar would take Pac.
The very basic MMA techniques can be learned quickly, Vitali already has Kickboxing and a grounding in Pankration from the Soviet system. I've no doubt Pac could be taught enough in one training camp to stay on his feet and pull guard till the bell if need be. He'd punch the fuck out of Edgar anyway.