Fighters who overcame all styles?
SRL, of course comes to mind here. In Benitez, Duran, Hearns and Hagler he bested opponents that were masters of their own styles (and just... masters). Hearn's must have been his absolute stylistical cryptonite, but he still overcame him. Would like to see Leonard against a WW-version of RJJ. That might just be a bridge too many.
Ali also bested just about all styles. He obviously had problems with swarmers, but still beat one of the greatest there been at HW two times out of three.
Robinson? He must have met fighters of just about every style, and since he seldom lost...
Greb should be mentioned here I supposse, but could someone fill me out on the details, please? Langford, Charles?
Feel free to name some more and comment on my choices.