As much as I like this design of Dragonite, I prefer the original more. It stands out from the other two and doesn't look like a bigger version of Dragonair. I like drastic changes in final evolutions. It's what makes Pokemon unique. In other words, I love that derpy orange dragon.
That theory doesn't make any sense. Whoever told you that hasn't done their research on Mythology. Dragonite is based on "Guardian of the Sea". A Japanese myth/story about a sea serpent(Dragonair) that changed into a dragon(Dragonite) that protects the seas. Gyarados is also based on a Japanese myth/story about a carp(Magicarp) that changed into a flying water dragon after attempting to climb a waterfall to prove its strength.
-Mudkip went back to a quadruped in its final form.
-The "limbs" on Snivy and Servine were outstretched leaves/limbs. In its final form, these limbs turned into leaves they were meant to be. (though its coils cover what grasping abilities it used to have.)
^^Just wanted to point those factors out.^^
They do look more creative with changes in their final forms. However, I do take some offense to that last remark, "I'm looking at you fan-artists," as I am one myself.
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.