Wow, really unique match. And a pretty close one, too. Both characters have similar tiers of strength and durability, and either of them beating the other down does seem feasible. However, in this match, I believe there are two reasons why the Man-Crab may just pull ahead of Crabrante. One, Bud has a fairly higher intelligence level above Crabrante, being a mechanical genius and able to plan the whole sceme he pulled during his time on the beach. However, considering this is planning ahead of time, and eventually the Mystery Gang was able to crack down on him, I'm just giving him a slight edge here.
However, the biggest reason why I would think Crabrante would lose is his completely obvious weakness, being his eye-stalks. All the Man-Crab has to do is grab his eye stalks and pull, and all of his guts would come out. In fact, he'd probably be able to do this merely by accident, and not need to try as hard as Saitama had to when he killed Crabrante. As I said, it's a very close match, with both of them having almost equal stats. However, I do believe this one Achilles Heel will prove to be the downfall of this minor villain, meaning Bud's gonna have crab legs for dinner. (Technically, Crabante is still human from the waist down, but still...)
Winner: Man-Crab