War-Hulk is dangerous because he is the present incarnation of Maestro.
The intelligent, cold, caculated, Hulk, that has no desire to spare the lives of Earthlings wether friend or foe. This does not make him pre-cisis Superman level, only a much more fearsome opponent.
Captain Universe hulk is just a bit overkill, Hulk can jump so high he doesn't really need to fly, he's already got super strength, now he just has x-ray vision and cosmic awareness to sense danger. I wonder if he can sense that pre-crisis Superman is capable of destroying the whole planet with a falcon punch?
Devil-Hulk is simply Maestro but taken to the extreme, no inhibitions, no feelings, just a mad genious bent on mindless destruction. A frightening combonation ceartainly. But one pre-crisis Superman could handle.
The three combined might possibly be able to take-down Supes, only because pre-crisis Superman never excersizes the full extent of his power.
However, they would have to work as a team. I do not see this happening. Pre-Crisis Superman may just be able to use the mental isntability of all three of the banners against them. Not to meation Superman is faster then all of them.
I'll say this much: This would be a better fight then anything Pre-Crisis Superman encounterd in his 1950s comics. These are the kindsof abomonations he should be fighting instead of nazi mecha and guys with toy-looking lasers.
But Pre-Crisis Superman is just way too powerful.