Buffy vs. John Constantine
Two smiters of evil with no small amount of experience taking on, and out, the worst scum of the multiverse (an exaggeration maybe, but eh). A competition in two parts -
1st - The two must battle 100 assorted demons in an abandoned city. These are drawn from the twos respective universes (no higher end bad guys though). So who takes out the most?
2nd - A match in an abandoned city (with the demons gone it is really empty now). No outside help, 2 hours prep time no other rules. Which has the skill and fortitude to defeat the other?