Nothing

For a palette edit, I would look in the C1 bank disassembly, and search for "Battle Backround"

An example of what you would want to be looking for is:
C1/1D0C: BF5016E7 LDA $E71650,X (Pointer to top battle background palettes)

Assuming you know how to navigate through a hex editor, and get to the above address, you would go to it and look where the pointers are pointing to, and experiment with changing the values. There are many battle backrounds, and I'm not sure at all which is which in the hex, or how many bytes are used for a map. I do know that they would most likely be around the very last of 'em though. I doubt there is anyone that could provide a real answer for what you want to do, as I'm failry sure nobody has done it. Well, MetroidQuest changed the palette of the final Kefka battle, the clouds to be black. I asked him about that, and he said he did not remember where or how he did it >_< But he did it by looking at the disassembly for battle backrounds, and experimenting & changing values.

I do not have any idea what byte to change to what though, as this is not a common undertaking. I did try and change the mountain backround's brown palette to a blue once, and was unsuccessful, although I did manage to make it look worse lol. I'm afraid you will have to experiment around some more. Honestly, I would try and look into figuring out yy-chr, and then follow Zeemis' graphics decompressing tutorial, as that would be a much simpler way to do it. It's also the -only- way to change the face, and actually decompress and edit the battle backrounds.