These properties if introduced into the mainstream continuity are going to interact with the mainstream continuity characters, naturally.
I can barely comprehend Rorschach v Batman. Ozymandias v Batman leads to one trumping the other which doesn't really work (which is why you never saw Lucifer v Constantine in either comic, and you will never see a Black Panther v Batman comic).
I wonder if this is because of the critical success of Pax Americana?
