I will allow seramas as they are bantam as long as they are not mixed with another breed :)
I stated purebreeds but they don't have to be showable or in the bantam standard. I have a copy of the 2006 Bantam standard so PM me if you need my help.
and as for the polish i am not sure - they come in LF and Bantams. according to the standard bantam polish are 26-30oz. do you know how much your polish weigh?