In a fight between a boy and girl of equal strength and size, I think the girl will win a majority of the time. The balls are just too big of a liability for guys.

Obviously if he gets hit in the balls, he’s done, there’s no way he’ll be able to defend himself while in that much pain.

So, he has to actively protect them, and that gives the girl a ton of leverage. If she attacks his balls, he has to block, and that opens up attacks in other places. If she’s skilled enough, she can basically use that leverage to control the whole fight. 

People think balls aren’t that big of a deal in a fight, but they really are. When it comes to the design of the crotch, girls have a huge advantage.