Okay, results are in. Hopefully this information is helpful, it was not my desired effect to get this info. I am still trying for my Hunter Green. Good luck and keep up the work on this mapping of chocobo colors.

Adamantoise Green + Valfruit = Slate Grey [5 feeds, 1 proc. Stable condition was Good]
Slate grey + Mamook Pear = Adamantoise Green [1 feed, 1 proc. Stable condition was Good]