An excercise in spriting

[Vipershark]

On the middle Ariel in particular, I can see that you improved some of the colors (particularly the skirt and dark blue corset..? thing) but you still need more.
The white sleeves of the shirt need to be hue shifted (they're all at hue 130) as well as the hair (which is all at hue 0) and the brightest highlight in the hair has so little contrast that I can't see it unless the sprite is blown up.

I didn't really look through the other two but on Kim Possible I can't see her hair highlight too much and the shirt's colors are so dark that they all blend together into a single blob of black and need to be hue shifted as well.
In short, give her more contrast.

Also something about Ariel's face seems pretty odd to me...
the left edge is just a straight vertical line and it makes it look like her face just sort of ends.