It's really unbalanced.
There's a whole one physical fairy type move, very few type combinations, and very few usable fairy type Pokemon (Togekiss, Azumarill, Mega Mawile, Gardevoir are the only good ones aside from Xerneas, whose movepool is too shallow to be good in Ubers but has too good of stats to be allowed in OU).
Hell, the only good non-mega Fairy Pokemon introduced in Gen VI are Florges and Sylveon, who are both entirely outclassed by Togekiss and Vaporeon anyways.
Of the types its super effective against, Dragon, Fighting, and Dark, most people will either:
A: Rather use an ice type move because it has more coverage and is more widely available
B: Rather use a psychic type move because it is more widely available
or
C: Rather use a fighting move, because there's only one physical fairy move in the game, and it's not a TM.
