Wizard: Genius level IQ. Capable of teleporting to places, arriving far faster than Iron Man can fly there. Able to bend relity, displacing mountains, turn Iron Man's suit into an Armani that is incapable of stopping any weapon, etc.
Cleric. Able to control lightning and weather, walk on the wind, hurt Thor with a +1 weapon, raise the dead(which Thor cannot do), etc.
Hulk does not have a genius level IQ. Banner does and he's not in control more of the time than he is in control. He's also not invulnerable, just really hard to hurt. An artifact or even a +3 weapon, which high level PCs have should be sufficient to hurt him. The Hulk is probably on par with a Tarrasque, which high level groups defeat.
And would likely get his butt wiped by a high level barbarian in a fight. He's a giant. PCs beat giants all the time.
Wish can make those things happen. Edit: Armor of Invulnerability and probably a few other things can make one invulnerable to mundane weapons.