You can run a RBY server on ShoddyBattle. In the server.properties file, the server.metagame variable is set to platinum.metagame. You can change it to advance.metagame. You'll be playing the RBY metagame. There is no way to run a server with D/P/Pt/HG/SS, and have a way to play RBY only (unless someone programs an RBY clause.)