with legs. When you see punch coming (after few shots you could already know if he will aim to plexus), jump out of range and come back with left hook. If you cant read it, **** it, block it with your elbows..
one of the ways can be reflecting his punch, its hard but you can open him and counter also. its for all body punches
and maybe you could try to parry that punch with the same side arm, its very natural to parry straight punches so maybe that would work.