Pyro was floored by a knee strike in his Guts by Bruce Banner. Not Hulk, Bruce Banner.
Maverick has fought Sabretooth, Omega Red and other mutants. Pyro, besides his flamethrowers, has basically nothing, and his flamethrowers can be disrupted.
Maverick outakills and wins. He has enough agility and speed/reflexes to dodge Omega Red's coils.