I've seen a local breeder mix different kinds of clownfish in a 15 gallon. He presently was trying to get a clarki and occelaris together. They stayed apart for the most part, but the clarki would occasionally take a run at the smaller occelaris. There was no damage to the occelaris.
Long term, he is hoping that they become a breeding pair. He was saying that he had to make sure the larger type of clownfish was older and bigger than what the smaller type would become. In this case, the clarki was older and bigger and the occelaris was the smaller of the 2.
WDLV made a great list. I wouldn't risk this with a tomato or maroon.