They have the possibility to associate with all sorts of corals ranging from hairy toadstools to frogspawn/hammer/torch corals. And anything inbetween. It is ultimately up to the clown though and they may or may not take to any random coral or object as their host.
If you want a nem that is likely to host your clowns and not to hard to care for, the Bubble tip anemone (E. Quadricolor) is your best bet. It is one of the most common anemone in the hobby, pretty easy to obtain for a decent price, and while it does not host A. Ocellaris in the wild it is very common for it to host them in captivity, but the bond may take longer than a natural host.