Let’s start by saying that this would be a sanctioned match and not a fight to the death, as Deadpool can’t really totally die. I mean, he can, but he’ll come back. A lot. Even the Death of Deadpool from Issue #250 involved two planets colliding, not so much killing Deadpool as getting rid of the stage upon which he did (a sizable portion of) his work.
A world-class “fighter” against a former heavyweight champion would be worth the price of admission, but with the ring mic’d, we could be in for a real treat. Out of all the potential fights on this list, this is the one which would probably provide the most entertainment. At least as long as Deadpool could stop Brock from breaking his jaw (over and over and over again).