There are no colours that are breed exclusive, but there are some colours that breeds don't have.

For example, KNN's don't carry any of the pinto genes or the grey gene, while RID's cannot be captured with frame overo, and TB's cannot be captured with the dun or tobiano genes. Most breeds like X, RID, WB, TB and AA do not carry the LP gene for appaloosa.

I'm pretty sure that KNN's are the only breed that actually doesn't have the genes in the gene pool, grey and the paint patterns, although, as I said, LP is not present in a lot of the gene pools. I think it's only present in KNN, PON, ISH and SH.