Ok, I have 2 ideas for colours :3
The first colour looks like the creatu is covered in smoke so the creatu would be black or dark blue and have smoky tendrils or swirls of shadow around them, the idea would be that maybe when you ressurect a creatu you could get a cloak of shadows or shadow paint that you can turn your creatu this colour. The name could be Miasma (name created by Boonys13) and you could have more chance of obtaining the paint or cloak at halloween (idea forwarded by Omenaapple).
The second idea for a colour would be that the creatu is semi see through, e,g, faded maybe only in the legs and tail of a gondra.. the overall colour would be white or pale gray and the creatu would have swirls and circles of maybe blue or purple. The name of this colour could be something linked with spiritual or mirage? This colour could be a very rare hatch colour, this isn't really a finalised idea so people feel free to modify :)
Please let me know what you think of these ideas :)