Biggest genetic freaks in each weight class?

We know that Jones was a PEDs user, we don't know that all of his opponents were. His legacy has a question mark.

 

We know that Toney and Mosley and others were, and they didn't come close to prime Jones in other worldly speed. Mosley in hand speed, but not the overall package.

And then there were his extraordinary reflexes, which certainly wasn't due to steroids. Also, as others have stated, the speed he had already in the amateurs.

 

As you like. He had more than reflexes, and it very well might have come out of a bottle.