Okay so here's an example of the sprites being too big:
The Magikarp in particular is MASSIVE.
Now here's Chaos Rush's resized sprites:
These are scaled down to match the GBA sprites in size.
Now here's the two side by side:
Imo, the one on the right looks a lot better. :)
(Btw don't worry I never hacked your ROM to change the sprites, I just edited a screenshot on paint.)
Also, will you ever be adding gen IV and V Pokémon? I want to evolve my Togepi eventually into Togekiss.