I'm not very good with critiques, but here goes. Seems like most of the Fakemon designs are pretty decent, but there are a few evolutions that seem pretty "generic" to me. I think they'll fit pretty well with the fanfic.
The fire-snake one's(sorry, forgot the name) evolution is an example of its design looking a bit "generic" to its pre-evolution. Maybe having it, and other Fakemon based on mythology(like Altaria is based on Peng, a Japanese dragon bird) or a reference to culture(like Emboar is based on Chinese culture or the Chinese boar). You can always look up images and/or old myths to give you an idea.
I hope this helped in anyway. I did the best I could.