He definitely needs some more form, that's the first thing I noticed. Use more shadows around the sides, stronger on the right side and toward the bottom, to indicate curvature and depth.
In terms of shape, His cheek is a little bit sharp and the ears seem flat along the bottom (the ears, not a big deal if that's what you want it to look like). There's a point where the curvature on his tale stops right toward the base, that should be corrected, and the sharp angles it follows could be rounded out a little bit more too just by adjusting them by a few pixels. The base of his tail should be thicker, it's quite a bit more thin than the section of tail leading into it, so keep that in mind when you're fixing its curvature.
Your outlines are nice, maybe a little soft on the light points and definitely too dark in the shadow areas, but otherwise very consistent. There is a slight change in thickness on his left arm where it overlaps his rear leg, you should drop the corner pixels - you want a / not a L if that makes sense. Same thing with the whiskers, unless you want them to look a little kinked/frizzled.
The pose is great and perspective looks about right for a battler, and the style is consistent across the whole sprite, so props on that. Very good overall for a first try. :D
