aside from Sylveon (and we don't have confirmation on its stats and movepool yet), all of the Kalos-native Fairy-types are puny, cutesy, very weak-looking things. Unless they have some good evolutions and Game Freak puts out some tougher ones that don't look like they were drawn by a 6 year-old girl, Fairy will still pose a very small threat to Dragon while justifying the disrespect many have been directing toward them.
Also, the other Kalos-native Fairy-types we've seen will most likely get better with evolution.
Forgot about Xerneas, but I usually exclude legendaries from my little rants anyway since I never use them anymore. I'm sure the pure-Fairies we've gotten so far will have evolutions (excluding Sylveon and Xerneas of course), just it's a question of if they'll be viable for a main team or competitive battling. Of course all we can do is wait and speculate, but I'm not expecting very much from them right now.
Playing) Fire Emblem: Awakening, Guild Wars 2 Waiting) Pokemon XY