just something i'm working on..

[Vipershark]

I liked my sprite looking like a 90's/early 2000's game instead of Pokemon #2239 of today.

That's fair, but you have to keep in mind that even back then there were a lot of games with bad sprites.
There were inexperienced and/or lazy spriters then just as there are now, and the sprites didn't look good then and they certainly don't look good now.
Bastendorf brought up Mario World as an example of pillow shading used correctly, but that's not true. Pillow shading can be found all over Mario World (and in most of the contexts it's used it it doesn't belong at all) and looks just as out of place there as it does on your sprites. If I remember correctly, SMW's light source is in the top right and Mario and many objects are shaded to reflect that. Then you have other objects which are pillow shaded or pretty much unshaded completely, and...
Graphically, it's kind of a huge pile of crap.

It might be a classic and it might have been one of the high points of spriting years ago that everyone wanted to be like, but in recent years people took the time to look at what's really going on with the graphics and realized that SMW is a really bad-looking game.
Technically speaking, of course.

Anyway, back to your sprite.

I don't really have much to say (since it's still not finished) aside from the fact that your two darkest reds are so close to each other that I couldn't tell the difference between them at first.

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is this actually a sprite thread

Either actually contribute to the thread or don't say anything.
Warned.