One thing to remember is most if not all will defend a territory.. Some just defend larger areas. I try to keep the smaller members of the family Chrysiptera and Chromis( many look like damsels, but alot less aggressive)... I DON"T recommend fish from the families Abudefduf, Neoglyphidodon, Pompacentrus and Dascyllus unless you have a large tank. With fish there are always exceptions, but for the most part this has held true for me...also I will never add a sixline again!
In his first post the yellow tail was fine until the Domino was added..