This is something that’s virtually impossible to implement into the server. Luigi and Dr. Mario are two completely separate bosses with their own configs. There’s no way to shove their configs into Mario’s and somehow have them as reskins for the boss. They’d have to be added as their own bosses to function properly.
Also a side note: if you’re going to make these suggestion threads, I’d recommend actually putting them in the section of the forums labeled “Suggestions”.