It's fine to limit the amount of shades you use, but you could certainly make more use out of them. Especially the darker ones for AAing.
which is what you should work on first imo. of course, poor AAing can make the shading look blurry...that's because its poorly done. Good AAing takes practice, and its not simply putting one pixel or line of a dark shade next to the outline. I suggest you find some good AAing and study it.
Also, black can certainly have as much depth as any other color. it just needs a noticeable amount of contrast.
one more thing to be nitpicky about is that the yellow/blue on umbreon needs to also be AA'd with the black to lessen the conflict between the two colors. it looks rough right now.
which is what you should work on first imo. of course, poor AAing can make the shading look blurry...that's because its poorly done. Good AAing takes practice, and its not simply putting one pixel or line of a dark shade next to the outline. I suggest you find some good AAing and study it.
Also, black can certainly have as much depth as any other color. it just needs a noticeable amount of contrast.
one more thing to be nitpicky about is that the yellow/blue on umbreon needs to also be AA'd with the black to lessen the conflict between the two colors. it looks rough right now.