I don't think that Groo ever met any of them, but with his personality, consisting of an almost childlike innocence combined with a pit bull loyalty to Cordy and anyone that she cared for, I believe that he would have almost certainly tried to eliminate them with extreme prejudice, or at least have offered to.
Course, that's just my personal opinion. I'm sure hat there are contrarians lurking about who would not hesitate to disagree.