Just found this thread now.
My honest opinion about the fairy type is that having a dragon immunity is broken, at least in terms of the current metagame. Blissey and Chansey, two of the best special walls in the game period, now CANNOT be phased or take damage from Giratina-O's Dragon Tail. Add on to this the ability to reliably wall Scarf and Band Outrages and Scarf and Specs Draco Meteors, and Fairy type pokemon nullify the core nature of the uber tier - powerful dragon spam.
Anyways, here's a list of the pokemon that I think will be the best if they turn out to be fairy type and the fairy type turns out to provide dragon immunity. Every pokemon has a physical defense buff from the damage nullification of Outrage, so I won't mention that.
Chansey & Blissey - Fairy type has amazing synergy with them. Weakness to Steel and Poison is irrelevant because they already lose to those Arceus forms. Now beats Arceus-Dragon.
Breloom - Palkia counter.
Roserade - Palkia counter.
Celebi - Palkia counter.
Shaymin - Switch into Dragon attacks and build up pressure. More reliable offensive check to Palkia.
Claydol - Zekrom has met its match.
Whimsicott - Switch into Dragon attacks and be an asshole.
Cyrogonal - Amazing spinblocker. No longer fears Giratina-O Dragon Tail.
Jynx - Palkia counter. Incredibly difficult to kill.
Froslass - Dragon immunity gives tons of free turns of setup if played right.
Jirachi - Not a massive benefit but a pretty cool addition. Once again forces pokemon that would run Dragon Tail to go Roar.
Manaphy - The Calm Mind set got a lot harder to revenge kill and found many more setup opportunities. Forces pokemon to run Roar when they would have ran Dragon Tail.
Arceus-Steel, Genesect, Dialga, Excadrill, Scizor, Heatran, Ferrothorn rise in popularity.
Hidden power steel is used on select pokemon with no steel moves, the same way hp fire was sometimes used, especially on calm mind pokemon
Oh and Fairy type is inherently gay so I don't really like it.