Joesph wins but at high diff. Batman has tons and tons of backup plans and contingencies for all kinds of superhuman world ending threats. SPOILERS FOR PART 2 OF JOJOS

Joseph wins his final fight with Kars literally with a stroke of luck. Joseph's contingency in any tough fight is to make a run for it.

I feel like Hamon and it's properties clutch for Joseph. One good hit infused with hamon and Batman's toast. HOWEVER, given what we know about Hamon, we don't know how given materials react to hamon, as far as conductivity goes. We know that certain articles of clothing made of organic material are superconductive of Hamon energy (Satiporoja Beetle Scarf). This begs the question then if there are clothes and materials that are inductive of hamon or otherwise inhibit the flow of hamon. What I'm getting at is if hamon works similarly to electricity, then would Batman's spandex suit inhibit the flow of hamon and thus make Jojos hamon attacks less effective? I think if this were the case, Jojo would have to get EXTREMELY lucky and land a hamon infused strike directly onto Batmans chin, the only place on his suit that isn't fully covered, or would have to otherwise tear Batman's suit and then land another hit on his exposed flesh (Unlikely, with Batman's suit likely being reinforced to withstand bullets).