Fluffy made very concise points in his analysis.
In raw AP, yeah, Gen is stronger, and he seems to use his pressure point strikes in general (I'll come back to what I mean "in general") better than Bang, as most moves in Gen's arsenal are dependant on him hitting areas as small as his fingertips, and he does that consistently even against characters that are equal to him in attributes such as speed, if not superior, and fully expects him to do so. Bang's pressure point usage seem to use his whole fist to hit more vulnerable areas of the body. Again, this isn't exactly hard evidence, fiction makes it possible that the fist transfers more energy, but in SF logic, Gen delivers the force of a closed fist using his fingertip alone in a smaller area, so he gets more out of his AP than Bang does using pressure points. This is amplified by Gen's damage boosts and harder-hitting attacks. However, there are specific problems. First of all, Bang has one move, the Kiba Soshi, which seems to be abnormally precise and should be superior to most of Gen's strikes, and Bang himself has plenty of enhanced moves as well. Plus, in LS, Bang is vastly superior. To be fair, I do not remember LS being very relevant to Bang unless you went to grapple with him, as the Water Stream Rock Smashing Fist style is mostly based around striking alone. So, unless Gen deliberately went for a grapple, which he should notice as being a stupid idea, LS shouldn't play out significantly in this fight.
One interesting here is that, for once, stamina will be a heavy factor here, and Bang beats Gen here veeeery badly. While it is entirely possible that Gen may last a long fight, he'll be the more tired one, and there's always the possibility from the illness to attack even at the start of the battle.
Speed is equalized and, for one, Gen is actually the more agile of the fighters, which is rare for most SF characters, although Bang can leap and dash way farther than Gen can, which can provide some interesting scenarios.
Skill-wise, while I think Gen is the more experienced one against other martial artists like Bang and himself, a more precise fighter and mayhaps even have more willpower... I'd be hard-pressed to say that Bang is less technical, or that his willpower is smaller enough for this to matter in this match. Bang is exceptionally talented, trains a lot and consistently tests his style. I'd say that, if Gen is more skilled, it isn't by much, nor is it that big of an obstacle to Bang. Besides, Bang's considerably harder style of fighting might broke tough for this incarnation of Gen's style of fighting.
In powers and capabilities, while Gen has plenty of very good tools, such as the stunning and crumpling strikes, Bang is ultimately the one whose powers better match him for this fight. His Awakening skill, plus all the other stuff such as Instinctual Reactions, should benefit him.
All in all, this is a strange case of a more precise and stronger fighter fighting against a more fragile, more agile and almost as skilled fighter. If Gen tires up quickly enough or accumulates too much damage, Bang should win, but if Gen catches him with a good combination of strikes, Bang goes down. In this scenario, I bet on Bang more times than not.
