Are you a breeder, dog trainer or dog handler?

Because that's not how it works. You can breed for particular traits, as you mentioned, but behavioural characteristics (such as aggression) are more complex than simple genetic traits. You could breed two highly aggressive dogs together and get a placid dog as a result.

You're talking about behavioural characteristics, not skills. Dogs don't know how to fight without training any more than people know how to drive a car without lessons.

And as far as aggressive behaviour goes, pitbulls aren't necessarily any more or less aggressive than other breeds. There have been lots of studies on aggression in dogs that show that breed is not a good predictor of behavioural tendencies (https://pmc.ncbi.nlm.nih.gov/articles/PMC9679229/).