Well, I played around with PokeTEX, and it indeed can change graphics. (in the Japanese version at least - haven't figured out how to get it to work on U.S. version).
Anyway, I've got a few screenshots of it, in which I changed a few graphics.
Enjoy!
P.S. Oh, by the way, the Ideas emulator now works perfectly (or close enough anyway) with Pokemon diamond. You don't need the (*illegal*) bios and firmware files for it, either. And, it has save states! :D Might just be passing up no$gba. It's fast, too!
Edit: Just realized .bmp files won't upload. So, I zipped them and am attaching them now...
Edit: Figured out how to make PokeTEX work with English roms, but it's a pain. Took me hours to get. I'll post how to later when I have time.