If you don't know the character, read up on em.
Dante has his sword, pistols, rail gun, shotgun, grenade launcher, Beowulf, Cerberus, and Yamato. He has access to all of his moves (EXCEPT for Quicksilver).
Ares has standard equipment (sword, axes, spears, grenades, guns, etc.), and CANNOT be revived by Zeus or anything else.
Fight takes place in the Colosseum. It is (as Gambler once described) a "Old West" showdown-they start a fair distance away from eachother and are told to fight until one falls.