Koopalings Custom rpg sprite

[Vipershark]

Do I still have to work on the colors?

...uh, yes?
As far as I can see you never changed them, but even if you did, the colors on the rest of the koopalings need work too.

The problems is the contrast?

Not just that.

Anatomy issues aside,
First off, you've got waaaaaaaaaaaaaaaaaaaaaaay too many colors on this sprite.
I can count 18 different colors in use here, and for a sprite as small as this, that's like... probably more than twice what you need.

You can optimize your color usage better by sharing colors between the face/stomach areas and the arm/leg areas since the colors are so similar.
You can also combine the blue of the hair and shell with the green of the head because the green is in such a small area that it isn't very visible anyway.

In addition, there's banding and pillow shading everywhere which you need to get rid of, and your sprite needs a whole lot more contrast as well as some hue shifting.

Basically every single one of these sprites has too many colors and not enough contrast, hue shifting, or variation in saturation levels.

Every single one of the shells has pillow shading on the back poses, and your shading needs work in general.