Most of the issues I see are with the Naota piece. When shading things like faces and clothing, the shading shouldn't come down in a straight line like that, but instead it should follow the curve of the face/piece of clothing/whatever. Things like eyes also need shading as well, especially the iris and pupil, in anime-like pieces.
Other than that, the only other issues I see are with the jolteon - the neck ruff could've used some shading. If you shade one area of something, shade all the areas, or else the unshaded area will look extremely flat when compared to the rest of the piece.
Those look pretty good otherwise, though. ^^ You've got some good lineart there.