Hi good day, Alfred E. Neuman will be proud of you.
if you want my advice, I think that you could keep it more simple, the original character design are simple and a little more geometric with thin shoulders they torsos are more like triangles,
No shadows, no strange angles, and thick line, you can have both characters just for make one of them, just only need invert the color in some outlines and regions of the vector model and you can have some like this:
here is the .sifz file if you want to see it. SpyVsSpy.sifz (27,9 KB)
you can change the expressions and hands with some switch groups
Im Working in an animated short too, but Im using limited animation for the moves because the designs are a little more complex (The BG was make using a 3D software)
I have the eyes, eyebrows, mouths and other elements of the characters in switch groups or hidden
Here is the .sifz file of this one if you want see it; Hera.sifz (131,1 KB)
an this one for the walking cycle: Blue-Walk.sifz (130,7 KB) just with making some rotations and displacements of the pivots it looks a little more animated.
Anyway this is just an advice and im talking from the point of view to try to make more using less (limited animation) you have to take the final decision, and if your idea is make some to look more like full animation go ahead is your project and dont feel forced to make changes if you dont want it. 