Hi Lumelore!
I like the idea. You've picked a great example for this sort of anti-aliasing.
My eyes are noticing three main things:
-The texture in the wing, chest and shoes. If you compare to Kirby, it's all smooth. To achieve such a look, I think the texture and extra detail needs to go. No use spending extra colors on these.
-The color choice. If you look at Kirby, the saturation of each color is quite heavy on the dark hues. Each color pulls its weight. Compare to yours we are getting a "flat" feeling. Consider the colors being used to anti-alias.
-Where to place the anti-aliasing. On Kirby, the anti-aliasing is to help build the shape towards the outline. The "inside" of the character is being anti-aliased towards the black outside. On your character, the anti-aliasing is being used to smooth out volume, but not to build a volume shape towards the edges and outline.
