So, swellow is a great fast Pokemon. With the ability bold, you're raising defense and lowering attack which is good and bad. Good because he needs the defense, and bad because swellow majors in attack. So, kinda balances off.
The sharp beak increases the power of flying type moves. You have 3 flying type moves which basically gives you a huge advantage, and also a replacement for the lost attack. I think, attack wise, you should make fly or brave bird your main move, since it swellow excels more in it. But, the sharp beak could really help you too. But, it can also give a boost to the other moves too.
The King's Rock is responsible for a probability of flinching when making contact. Seeing that you use air slash most often in battle, the king's rock is useless - unless you're willing to use fly or brave bird more often. A lot of people love the king's rock but mainly for physical type moves.
So, I strongly agree with your choice because the sharp beak has a lot more effect. The King's rock can only cause flinching, but if you look at it, air slash can cause flinching too.
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