We have a watchman goby
and a pistol shrimp
which reside in the same hole. They are fun to watch and fun to feed. I think the pistol shrimp may be questionable at times, but ours is docile. He just hangs out in the whole with the watchman and then they eat together.
I have heard of trouble with maroon clown and perculas in the same tank. Has anyone else heard of this concern???? I am not an expert, but I would look into that.
We also have a true percula and a black and white percula. They are really pretty together. And reef safe.
Live Aquaria web site has a lot of information on fish. They list agressiveness and whether or not they are reef safe. I also think the size of your tank matters with aggressiveness of fish.
Again...I am not an expert, and I am sure a lot of others have more experience to give, but this may help.