Iron man, war machine & hulk vs the world of normal human
All world and the weapons vs iron man wm & the hulk with them only having a secret hideout they can use for only 2 hours at a time to heal and restock weapons.
K so eventually the world's military would overpower Iron man, so he's out.
If by "all the world" you mean the world's scientists... someone out there (probably in S.H.I.E.L.D.) is bound to know about Hulk/Banner and how he changes.
Takes one brilliant mind to figure out a way to soothe Hulk to weaken him and have him revert to Banner... then it's <die>.
World wins.
NOW, if this is the retarded PIS world of WWH, then they have no hope, because even the heroes were eat up with the dumbass.