Alright I made a summary of where Urouge is for everyone.

BASICALLY when he returns he'll have Lunarian flame powers, his OP Birkan martial arts which a single monk was able to use to fuck up the monster trio, and his devil fruit that turns whatever damage that does get through into raw strength.

Urouge will be Luffy's Whitebeard. It was already foretold during WCI when it was said Urouge was the only supernova capable of taking down a Sweet Commander.