[{quoted}](name=Eevee Girl Alex,realm=NA,application-id=9hBQwnEU,discussion-id=APAhcKhA,comment-id=00030000,timestamp=2015-10-11T04:00:13.997+0000)
They do 2x damage to Dragon-Types, but Ice-Types are usually statistically awful and DON'T have Dragon resistance for whatever reason.
Two of the strongest dragons in OU have a 4x weakness to ice though: Garchomp and Dragonite. Altaria has one too before it Mega evolves, so if you hit it on the switch you're going to devastate it. Weavile, Kyurem-Black, and Mamoswine are strong Ice-types in OU, and some non-ice types, such as Starmie, can also run Ice moves.
Fairy was, unfortunately, necessary to put Dragon-Types in check. But with the addition of Fairy-Types, it brought both Dragon-Types AS WELL AS ITSELF DOWN, with the exception. Fairy-Types are rarely run, to my knowledge at least[...]
Clefable is incredibly strong, as are Mega-Altaria, Azumarill, and Meda-Diancie. Fairy type is one of the best defensive types in the game, with only two weaknesses: Steel and Poison. Fairy types alone have made some Pokémon bring Poison moves for coverage.
(Also, side opinion, Sylveon is the worst Eeveelution, IMO.
Perhaps from a design standpoint (although all Eeveelutions are pretty good looking, so it doesn't say much), but it's the strongest Eeveelution from a gameplay point of view. It's the only one that's currently decent in OU, after all.
Note that I only care about singles. I'm not really a fan of doubles or triples.