Well, let's start, first we have Ben 10's Atomix, he has nuclear powers,flight and well, powerful energy. Forces. He takes a superhero kind of appearance and behavior but still has lots of intelligence in him. Being able to 1HKO an evolved vaxasaurian, and is also Ben 10's Atomix 2nd most powerful alien,possibly even the 2nd most powerful alien species in the universe.
Atomix's species are overconfident, a lot
NOTE: I am Counting Atomix without time limit,breaks, or switching, since Ben does that a lot, but during the battle, Ben will be stuck as Atomix.
Well,next we have hulk, who, has super strength,a healing factor and possibly super powered lungs along with rage controlling all of it.Hulk's hands are capable of the thunderclap, his rage also makes him stronger, since the angrier he gets make him stronger.Strong enough to carry New York City and other things.
weakness: hulk has big lungs,this can also make him vulnerable.also,Hulk has low intellect.Hulk also has limits in breathing in space.
The winner is Ben 10's Atomix, Hulk may have an advantage in physical attributes, but Atomix can take out Vaxasaurians,evolved ones. Also, hulk still counts as vulnerable to kinds of intergalactic opponents,which makes Atomix superior.