I'm not too comfortable with giving criticism cuz i'm new to spriting too, but a couple of things i've noticed:-
Scratches:
1. Needs more shades. If we can use 15 colors in our sprites, and the sprites have only one or two colors, use more shades to give it a more life like look.
2. The outlines are jagged, try rounding the edges and defining the outlines. (Some parts, like the tail of the snake pokemon, the rounding isn't done properly.) Try to round it out on a pixel level (by making the top line have 1 more pixel than the next, etc.)
3. Tentatot's lighting seems strange, and the body either has a too thick outline, or none at all.
4. The cat's belly shading is wrong too. It almost seems to stick out. If its just different colored fur, the shadings on it should match the rest of the body.
Splices:
1.Look good to me, your onix splices look, imo, amazing.
2.Lapras evo looks good, just work on the outlines on the shell spikes
Simpsons:-
1. they look pretty good, but the outline's on some of the roofs don't seem symmetric and some don't have any shading.
2.The french windows need shading, cuz they look really flat and don't stick out at all
Koffing:-
The koffing is alright, the shading is wrong because your still going by the old sprite. Koffing is spherical and that means you gotta shade according to the curvature, not the way the old sprites did it with their lack of colors.
Pie:-
The pan looks pretty good.
these things are the things that i try to correct in my sprites as well, so i thought i'd share.
Scratches:
1. Yea, the only good shades (which imo still suck compared to others) I do are in the Fakemon Thread in the Pixel Projects section. I really have no need for my own Fakemon. so I don't really care for their quality. If it were something per say a large project like a PO, an actually good MUGEN char from me, or something like fully custom tiles, tehn I would try the hardest I can (see my pie)
2. Something I really should learn no matter what I'm doing whether it be MUGEN or PO or whatever.
3. The was actually my first sprite ever and I never really anticipated it to be good but thanks, some day I hope to revamp it.
4. I don't see anything wrong with the belly other than the sucky outline and the top-right corner.
Splices:
1.Thank you fine sir.
2. Those are just stretched out Sharpedo horns and I was even worse at fixing outlines than I was now, I probably will fix this in the future.
Simpsons:-
1. I totally forgot to do shading on the houses roofs. The lines oncea gain, I know suck.
2.I'll put some shading under it to make it stick out. (I think you mean the bay windows on the Simpsons house, right?)
Koffing:-
I got lazy toward the end. I think I'll just connect the shades on the right side much like what I did with the fat cat's spherical body and make it aligned to the curvature.
Pie:-
Would you like a piece?