Pikachu WIP

[Video_Pochi]

Before I talk about the sprite, a little note on how improvement works. It does not go: "people don't like this so I should try a different subject" it is, "people don't like this, I should ask what to change about it to make it good." If you go with the first option, the next thing you make will have the same flaws, and people still won't like it. Then you'll make another, with the same flaws, and the cycle continues. You never get any better.

However, I feel that won't matter right now, because it's pretty good! You have made a rather pleasant(although slightly generic) Pikachu sprite. It is certainly not perfect though. Here's what you can do to improve:
I'll start with the lineart. You have a relatively decent grasp of lineart. Better than mine probably, I hate doing lineart. The body shape, the feet shape, the head shape, they're all fine as far as I can see. The problem areas are the tail, the ears, and his left arm. Let's break this down piece by piece.
TAIL: I see what you're trying to do here, but it didn't work out so well because of the spiky nature of the tail. Pikachu's tail is odd because it's actually made of flat, angular lines. Now, the main problems are on the left side on the tail. On the big part, on the bottom left, it bulges out. It makes no sense. It would be much better if it was just straight. The curve at the end, connecting the two sides of the tail, well, it should be a straight line. Straight, but at an angle, not just a 1:1 slant. The middle bulge on the left should also be pointy, but it's not hard to fix.
EARS: Well, it's a little odd seeing pikachu with one ear up and one ear down, but that's not really a problem; my rabbit used to do that. The ear that points up is fine, but the other one is pretty unsmooth. Just try to smooth it up a bit. Not quite sure how though. You could probably make the one pointing up a pixel shorter, now that I think about it.
PIKACHU'S LEFT ARM: Th problem is that it's flush with the ouline. If it had any real depth, it would bulge out a bit past the outline. An easy thing to fix.

Well, that's the lineart. Next up, the shading. You have a good grasp of lightsource, but you don't anti-alias at all. If you don't know, anti-aliasing is a technique used to smooth out hard lines by placing a pixel of an in-between color at corners of color. The best example I can give you is Mario & Luigi: Superstar Saga sprites. These use outer-AA, where you anti-alias the outline into the background. Look at those sprites on TSR and try to see where they place the pixels. You should apply the same concept, but inside the sprite. Now, I'm terrible at explaining AA, so please look up more concrete tutorials on how it works.
On the arms, you should put shading underneath them a bit, because if your light source is at the top, they would cast a shadow.
The shading on the blackof the ears is all weird. The shine should be on the top, not the bottom. Also, you can trash the really dark gray and just make it black like the outline. No one will know.
What's that little streak under Pikachu's left eye? It makes no sense, and get rid of the pink piece, it's just messing up your color count.
Use your brightest color a bit more. Put it on top of the arms, on the big part of the tail, maybe even on the legs a bit. Also, make the highlight on the head follow the contours of the head more; the shape of the highlight doesn't curve with the head enough.
The dark line right to the left of the highlight? GET RID OF IT. I know what it was supposed to do, but it does not do the job. Just erase it.

Well, all in all, a good sprite. Reminds me a bit of JoshR's pokemon sprites. As it is, you COULD make a sheet, but I recommend refining it before doing so. Good luck!

ok i fixed it up a little
But you can pic which ones you like

example: A1 B2 C2 ect...