I have a pewter female who I am planning to make my next alpha female and I was wondering how likely is it to pass on her pewter coat to her offspring? Is it completely random, or is there an actual percentage to go by?

Well, if you have an male who has an pewter coat and you breed your female with him. Then, the offsprings has a random chance to have an pewter coat

I'm going to correct the above to:

So, if neither of the parents have a rare/uncommon coat, there is still a very very narrow chance for the pups to get a rare/uncommon coat? As a sort of 'mutation'.

Yes

Alright, thank you all for answering my question! I hope I can successfully breed a Pewter coat of my own!