Well, you ARE pillowshading, and in general that is not a style but just sloppy/bad practise. There is no clear lightsource, straight on flash photography one would look different even.
I made a quick edit to raise some suggestions:
Do you really need the triple outlines? Everything looks like fridge magnets and super flat, not matter how you shade em.
I made the outlines change lightness depending on the direction of the lightsource which is top above (I know they would flip when the sprites turn but that usually still looks fine)
I mixed the ramps a bit, like the darkest colour before black can be used as outlines on the blue fine and be used as buffer from black to skintones.
Reduced colours by cutting out the grey, I don't think it's needed, tho that might be preference.
Added some dither for clothtexture and blending.
In total my edit has 15 colours.