So, we saw them fight in HoX/PoX, but it was their future versions, even further than the timeline that Nimrod originally appeared from. It was pretty conclusive that Nimrod won there, but he also had home-field advantage.
This time, we get a timey-wimey rematch of sorts, using their classic or most common versions (say, Nimrod from the 80s, Apocalypse at his usual strength and powers), set in the present day. Standard Arena rules apply. Who wins?