I don't keep nems anymore. Not at this stage, I just don't feel like dealing with it. However, that is not to say that I didn't enjoy mine when I did have them.
I also don't think it is a clear cut "it will, or it won't" thing. Anemones eat fish. It's a fact, they are hungry. But I have heard it stated many times that they will only eat a sick fish. As far as what they can eat, people here have said that their nems have eaten WHOLE tangs. So, could it eat a gramma or goby... of course. Will it? Probably not, unless the fish is sick and wanders into it's clutches... Or the nem is just THAT AGGRESSIVE.
I would venture a guess and say that all the most common nems I see are going to be green bubble tips, and rose bubble tips (Which are very pricey). I think they seem to be pretty hardy and will easily be hosted by the right clowns. And beware that sometimes, the clowns just don't want to host. They just aren't wired that way, or the nem is aggressive (Like mine was) and they got stung and now they won't go near it because they are scared.
Good luck!
I am sure that someone else will chime in.