dA FAQ #572 wrote:
What does deviantART consider "Fan Art" to be?
The type of fan art which is deemed acceptable for submission are those work in which the submitting artist has done 100% of the work. This means that the artist had started with a blank slate and perhaps a reference (a pose, character, location, or other source) and proceeded to draw, paint, or otherwise create every line and place every color with their own hand.
When copying from an established source it is considered good etiquette to credit your source. Also please note that it may be considered unacceptable to precisely duplicate another existing work by directly tracing or reproducing every single detail so that it is difficult to tell your work from the original, so please be certain to add your own personal touches and style.
Unacceptable submissions may feature screenshots, official artwork from a video game, scans from an art book, a photograph of a famous person, or similar items but in every case the source material is considered the legal property of another artist. In many cases these 'seed images' are manipulated, colored over, blended with other images, and otherwise digitally worked over.
Due to the fact that these pieces contain the works used without legal license we must prohibit their submission here. These unacceptable pieces will be removed as they come to the attention of the administration.
So I heard that crappy Sonic recolours and shiz may be removed in the long term, provided the dA admin can delete them as fast as they are submitted.
Good luck to them with that.