If you're planning on putting the plate coral in there for the clowns to host because it looks like an anemone, there is no guarantee that it'll work. Clowns will host anything they want. I've had a pair host my powerhead, and had another host a mushroom. However, most corals are not accustomed to having little animals smack them around and pull on their tenticles like clowns do to nems. IMO, a plate coral being hosted by clowns would probably not do very well.
If you want to try to get your clowns to host something that looks a little like a nem I would recommend some hairy mushrooms (cool green color too!) or maybe a toadstool (looks a bit like a carpet nem). Both are very hardy corals, unlike the plate. Like I said previously though, there is no garuntee that the clown will host in either of these as well, its just a bit safer for the coral.
