I, on the other hand, suggest more saturation; color balancing a pokemon card isn't an easy task; you need the art to draw attention over the rest of the content and not be overpowered by it; as talented as steffenka's drawings are, they're pencil-colored and photographed (I believe?), which gives them a somewhat muted quality for the exposure and amount of paper you see behind the penciling, which isn't so good when you're using them as a small part of a much brighter composition.
I could be wrong about this, since I never had to do this particular thing before, but perhaps copying the layer on top of itself and playing with the blending modes and tone/saturation could help you make the drawing more vibrant; the colors themselves are a fine combination already, yellow, orange, brown and orange, so your only problem is how muted they look.
Spiritomb looks perfect, color-wise; look at how the illustration pops out and your eyes are drawn to it; that was an excellent choice.
But, could it be that "Possession" is in a smaller size font than "Invisible Punch"? it looks that way to me, but not enough to be certain.
