I need to correct myself.
The only problem snake would be the phantom/mystic
The only single gene animals produced would be Phantoms and Lessers
On a side note, I don't know of anyone that can reliably tell phantoms and mystics apart. This is a breeding line issue since they are most likely two lines of the same gene. Lesser/Butter have the same problem. This matters mostly to breeders. For example, I have only phantoms in my collection. No mystics.