I finally managed to hack Emerald into giving me a new start map and preset Eevee as a starter right away from the beginning of the game, and autoset items. Maybe I'll continue. (It's fun!) And inserted a signpost explaining the controls. (Text copied from FRLG)
Now, to get rid of the opening Birch and truck movements... and make the music work.
I guess they'd have to be quite drastic palette changes, so don't post them if they're only slight palette changes.
In my experience, though, palette changing the official tiles never tends to go down well with others in general. It's quite hard to do it well, so... I don't know. Obviously it is up to you, but if you want people to like the tiles you use, I'd say either get new tiles altogether or don't change the official palettes.