I think Dante and Megaman will win, but it also depends on which version of Megaman this is. but for the most part they should be able to win. as for the nuclear bomb, they'll all probably work together to bring that down first so that they could fight for as long as they want.
in the case that they can't shut it down, they'll fight and as I said Dante and Megaman should win and be the ones to escape.
Originally posted by MooCowofJustice^This. The original Mega Man (and likely all other Mega Men with the exception of X) get crushed by Zero. There isn't a chance in heck that Dante can take both Vergil and Zero. IMO, he'd be very hard pressed to tackle Zero one on one.
Standard Megaman gets beaten by Zero. But Megaman X can take him without Zero's access to Sigma Virus.