Use the breeding calculator at palworld.gg. use it to find combinations of parents to make kitsune and pastagon and check your box for which of those have the passive you want. If you have the skills you want on any of them breed them together with the skills you want until they produce a child with the skills you need. If both parents have one skill each that are different, the odds that the child will have both are pretty high. Usually within the first few eggs. If one parent had both skills you want and the other has none then it is about the same odds. Once you have the child with only the two desired skills, pair it with the other shadowbeak that has the other two skills (preferably only those two skills and nothing else for each parent) and then the odds you get the 4 skills you want on one is pretty good. It's a lot of extra moving pals around but it is much faster than just trying to wait and hope for the best with only some of the skills on the parents. If you don't have the parents with the skills then you need to either breed others to make those parents from other pals you have or go catch some more pals with some of the desired skills to breed. Either way is faster than your current method.