Spark's Sprites

[Gors]

I finally could see this in a high-res screen...

my suggestion is to use a dark brown for outlines, not black. Pure black is 'too artificial' as I'd say, and since you're working with a small resolution art method, you'll notice that even if the anime's outlines are black, if you shrank it, the outline would become lighter due to computer algorithms calculating the average between the color and outline.

as for hueshifting, I'm stealing Previous' example:



hueshift consists on using the entire hue to your advantage, instead of just lowering and increasing brightness. Notice that the first Pikachu tends to red while the second is pure yellow. The hueshifted sprite looks better because in real life, neither the light or the surface that reflects it is purely white. This causes shadows to be tinted slightly. The usual is to tint the dark shades blue and lighter shades yellow, though it's not a fixed rule.