Tip: If you make a change to your ROM that you regret, just go to File > Restore > Restore ROM to Previous State in the menu. From there, you can select a restore point and revert your ROM to a previous state.
Hmm... based on your art, I'm trying to incorporate that into an ExGFX file. Not sure if I can do it. I'll inform you.
Edit: The eyes are done. Is it safe to overwrite the big boo tiles?
The mouths are done, too. Now for the body. I hope I can do it. I hope the coder can use what I drew.