Keep in mind that while clownfish will use a lot of different corals, as a host, it's not always healthy for them. If your clowns are using corals and start to show dark splotches on them, it's Hypermelanization. Hypermelanization is caused when clownfish use LPS and some soft corals, as a host. It doesn't seem to do any damage though and reverses itself when the clownfish and offending host coral are separated. Hypermelanization doesn't always occur when clowns use a coral as a host, but is something to be aware of.
Oh, another thing...
Clownfish do not host corals...corals host clownfish.