So let's just say that I have a pikpek with kings rock. It's ability is skill link, and it uses fury attack. Would the flinch chance be 50%? (if they all hit)
Yes. This is the usual strategy with skill link Pokemon, most Notably Cinccino as it gives 5 chances to proc kings rock.
I will note however that it really isnt 50% it's more of 10% 5 separate times.
Source: https://bulbapedia.bulbagarden.net/wiki/King's_Rock#:~:text=The King's Rock (Japanese%3A%20%E3%81%8A%E3%81%86,to%20cause%20Pok%C3%A9mon%20to%20flinch.