The major concern I have here is that the BSTs of most of these Fairies aren't very strong or are like, average. Also, the fact that offensive Fairy attacks, especially physical, are heavily lacking in comparison to other types. Because of this, I'm worried most of them may not cut it in OU due to the average or lower-than-average BSTs.
But one I definitely see making an impact is Togekiss, she walls both of Garchomp's STAB types and that effectively forces him to run Stone Edge just to have a chance of getting past her. Azumarill has also become the ultimate Palkia/Kingdra counter as Slim said.
I was surprised at how strong Florges was Sp. Def wise, she seems to be able to tank special attacks well based on what I've read.