Amazo

Amazo is an android who was created by the mad scientist Professor Ivo – a man obsessed with the concept of immortality – and he initially possessed the powers of the original Justice League members (Green Lantern, Flash, Aquaman, Wonder Woman, and the Martian Manhunter).

It has since been revealed that Amazo is capable of copying the powers of any metahumans that he comes into contact with and, as such, should be able to defeat anyone in theory, as he could acquire abilities in countless combinations.

Moreover, the character has more recently been written as being able to copy the powers of items as well as characters, which means that the array of powers he could potentially gain is virtually limitless – although it should be pointed out that he has yet to display the ability to absorb powers beyond a certain level.