Professor Ivo is a criminal mastermind and scientific genius, who created some of DC's most formidable androids, including Amazo, Composite Superman (who possesses the powers of Superman, Batman, the Atom, the Elongated Man, Firestorm, and Red Tornado), Red Volcano, and the telepathic Tomorrow Woman. Ivo by himself wouldn't be much of an opponent (though he did create a serum that grants him an prolonged life span), but something like Amazo could give him quite the edge against the Justice League. Amazo is an advanced android capable of duplicating the powers of metahumans. So, not only can he duplicate the power of Superman or the speed of The Flash, but he also has the ability to simulate other characters' weapons. That means he can artificially create a Green Lantern ring for himself, any number of Batman's gadgets, or even something like the Nth metal mace of Hawkman and Hawkgirl. Pretty awesome, right?