I was curious how a Mega Man Battle Network style game would work on the GBC, so I threw together a rough mockup.

A few notes:
- Reloads sprites and palettes mid-frame (several times)
- Uses smaller sprites to minimize sprite flicker
- The chip menu was altered to be horizontal. That way, it can use its own palettes and it doesn't obscure the battlefield.
- Uses sprite overlays for more colors in some places (portrait, chip illustration). Note that the mockup isn't strictly to spec in these areas (it's just to get the point across).

Overall, I think it's possible with some caveats (mainly sprite flicker).