Fight takes place on an artificial island in the middle of the Pacific. The island is a perfect circle in shape, and has a land area of 60 square miles which is divided evenly into 3 regions:
1) Jungle Area similar to Vietnam
2) Desert Area similar to Afghanistan
3) Large Modern City that is always in a state of darkness (similar to Gotham City at midnight). City is densely populated with 6 million people.
Each region is 20 square miles in size and borders the others (think of a pie chart divided in thirds for an idea). At the center of the island, where all 3 regional borderlines converge, is an armory stocked with every martial arts and conventional weapon imaginable, as well as a stockpile of Batman's arsenal.
All three combatants begin the battle in a paddle boat on the coast of the island and arrive at the same time in different regions:
Punisher: Jungle, armed with his usual arsenal (M-60, Colts, Sniper Rifle, Various Grenades, etc).
Batman: City, armed with his usual night patrol implements.
Rambo*: Desert, armed with a modified M-60 w/grenade launcher, his cross bow with multiple arrow head types, bowie knife, and frag grenades.
[* - Rambo is not allowed use of the Power Montage for this battle to make things even].
This is a match to the death.
No 'prep' before arriving on the island, but once they arrive they can set traps and use their surroundings for maximum effect, or they can make a B line for the armory. They can also move into the other regions at will and set traps there.
Basically, free range combat on the island. No vehicles allowed.
The Power Montage is an omniversal force that channels time, space, reality, spirit, and various cut scenes into an unstoppable aura of extradimensional energy of supreme intensity. It can bend creation itself to it's whims. With the Power Montage you can gain a millenia of experience, training, and superpowers in a span of moments in the actual space/time continuum.
Only certain people in every generation are born with the genetic makeup necessary to harness this power.
Rambo is a Prime Avatar of the Power Montage, only rivalled in his abilities by Dutch and Casey Rybeck, and surpassed by the Supreme user of the Power Montage, Rocky Balboa, who is the gate keeper to the Green Room, a nexus of realities and multiverses.