[Graphics] [PokeFireRed] unsupported color type error

I've been using the sprites from [https://www.pokecommunity.com/threads/267728] in my project.
However when I go to build the rom I get this error message by the time it gets to Beedrill:

tools/gbagfx/gbagfx graphics/pokemon/beedrill/back.png graphics/pokemon/beedrill/back.4bpp
"graphics/pokemon/beedrill/back.png" has an unsupported color type.
make: *** [Makefile:229: graphics/pokemon/beedrill/back.4bpp] Error 1

I have tried changing the colors but I still keep getting this error. Does anybody have some insight?

It seems the attached sprites aren't indexed (unless PC just broke the formatting when attaching them). If that's the case, you can fix the issue by using something like graphics gale to index them; they need to be 4bpp, and the front and back sprites should share the same palette. Alternatively, you could grab the sprites from the DPE instead, which should already have the sprites in the right format (apart from the names).

Thank you for the info,
Turns out I hadn't been properly indexing my sprites. Thanks for the help!

No problem!