Flower Pot corals IMO
are not a good idea for clown fish. Depending on the size of the fish and the movement the fish does in the coral It may not open. I have a FP and my small maroon clowns killed it in several months. They would bother the coral so much it would not open. No matter where I put the coral in my 125 the clowns followed.
What type of lighting do you have, this will determine what anemone type. Some require more lighting then others..
Also the FP are known to not have a long life span, most die after a year. They are great corals but not long lived.