I agree with everything except signature STAB sucking. At this point in time they surely must have learned to do good signature moves and abilities with few exceptions (looking angrily at Galarian Slowking).
Oh I don't doubt they have learned how to make good pokemon and move combos (See, Zacian and Calyrex, but also Urshifu, or Dragapult, or Toxapex if you're wanting defensive ones).
My question is, "how" good do they want it to be.
We are talking of a non-pseudolegendary, that's also likely available somewhere early in the game (I'm assuming thesse bosses will be comparable to Totem Pokemon where you can also catch their regular variants in the wild somewhere near the "boss" is), and isn't exactly looking like a very threatening entity.
I don't quite expect them to want to make Krawf *that* good. Hence why I think that it'll have "something" not that good.
A somewhat easy balancing factor would just be the moveset, and honestly i'd rather it have a mediocre moveset than have another Minior case which actually has a good moveset but isn't realistically ever using its ability anyway.