Ngata, sorry, symurgh should have an avian half. Your skin portrays a fox with wings but not a symurgh.
You may submit your custom here: http://beastkeeper.com/new-color-upload
Shihosa, it doesn't matter if the skin was created using the gradient tool or with manual blending if the result is the same. Though your skin looks proper for a unicorn (exploiting the cliche about rainbows and unicorns); it's simple but neat and carefully made, and we don't have a skin that uses rainbow on a unicorn like this. So this one will be approved. But this is a rare exception when such gradient works.
ameliahardt,
1) We don't allow using the approved skins for commercial purposes.This is a fertile source of potential lawsuits from other clients who bought the same image from you. Please don't submit the artworks that you plan to sell as prints or use for any other commercial purpose.
2) You're correct, we're sticking to easily recognizable species. It's not crucial (though desirable) for a gryphon to have bird paws since it still has bird head and wings. But in case of a symurgh with 4 canine paws, canine body and canine head we will get just a winged wolf which is clearly not a symurgh.
S.the.Unicorn, I would suppose that your graphic software doesn't support multichannel transparency but the shadow is half transparent so it's not the case... Unfortunately, I'm not familiar with this software and can't tell why the edge of the artwork doesn't have anti-aliasing. Fixing it at this point in PS or GIMP will look like carefully curing the edge with an anti-aliased round eraser. Please also make sure that you check your skin on black background before submission. The problems that may be unobvious on the light background are clearly visible there.
CynderAngel14PD, please post your skin here. I can't tell anything without seeing the artwork. There's a set of tech requirements that must be fulfilled if you want your skin to be approved.