I couldn't finish 'em. Looks like this's gonna get complicated.
??? is an enemy from Crisis Core -Final Fantasy VII-.
He is a copy of Genesis Rhapsodos and attacks with two curved blades. He can be taken down with a few sword swipes. If multiple enemies appear, using Assault Twister until they are defeated is recommended.
This enemy has exactly the same stats as the G Assassin, suggesting that it's simply a G Assassin that Zack fought before knowing what a Genesis Copy was, although there is no in-game explanation for how he learns their names.