Actually, palettes 6-15 change from map to map (although, I don't know how to use 13-15 as I've only seen them in HackMew's Animation Editor and not in A-Map. It's really too bad, I could use them) in Emerald, 6-15 in Ruby, and only 7-15 in FireRed.
I've been patient, too, by the way. I've been working on this game since October, slowly but surely. I know the styles aren't the same but that's the only place with B/W tiles. I couldn't find any other tree that presents the "forest" idea as well, either. AND, those trees are never seen next to any other type, so you kind of forget when playing, I think.