what do you mean by priority?
hark's sprites and concept belong first and foremost to him, and this applies to every contribution to the CS dex.
HOWEVER, some if not most sprites have gone through non negligible edits before being added to the dex, which essentially means that if and when you get permission from their original author to use them, you are not allowed to use the version displayed in the CS Dex. This is specially the case when the sprite is also credited to someone else (most often myself), in which case the difference should be more than noticeable for any "average and above" pokemon pixel artist, enough for me to consider my contribution substantial (as in "collaboration", in dA terms).
i hope that answered your question, if not, feel free to rephrase it