Hard one... how I think the battle would go:
Deadpool and Azrael face off in the streets of Gotham... no, wait.. make that a rooftop. Azrael does his whole "betrayer, defiler, Azrael will punish you" routine. Deadpool takes the piss. Azrael goes bserk and charges. Deadpool dodges. Punches Azbats. Hurts himself more than Azbats. Gets knocked back. Hangs off edge of roof. Azrael stands over him. Deadpool shoots him- no damage but pushes Az back. Deadpool would eventually lose though IMO...