"Amalgam!" from Marvel vs. DC #3 (Marvel/DC, 1996) by Ron Marz, Dan Jurgens and Josef Rubinstein
The fights were total bullcrap, of course. I wrote a rather colorful critique a few years ago. The only real coolness factor was the Amalgam idea, which saw Marvel and DC characters merging into neat (or clumsy) combo characters. The best Amalgam books? I liked Spider-Boy, Super-Soldier and Challengers of the Fantastic. The worst? Uninspired stuff like Legends of the Dark Knight, Amazon, and Magneto and the Magnetic Men.