Very cool, I like Houndour and Houndoom. Because of their Fire type, Houndour and Houndoom would take neutral damage from Fairy, as well as any other of Pokémon that has Dragon, Fighting or Dark that is combined with Steel, Poison or Fire.
Yup and there's a lot of Pokémon with those combos. They are Combusken, Blaziken, Monferno, Infernape, Pignite, Emboar, Toxicroak, Stunky, Skuntank, Drapion, Houndour, Houndoom, Lucario, Cobalion, Reshiram, Dialga, Pawniard and Bisharp.
Well, in a way they are, think about this. Steel is the only type that could resist Dragon type moves, but even Steel can take a lot of damage from either a Dragon Dance/Dragon Claw combo or a Dragon Dance/Outrage combo.
Also, many Dragon types can learn Fire type moves, most Steel types would be gone after a hit from a Special Fire type move since many Steel types don't have great Special Defense, expect Bronzong. But Reshiram can easily own Bronzong. So, I believe that's why Fairy was created for.
but water could learn ice moves most pro I know of use it to take out Grass types but it work with dragon too. Plus Dragon weak to itself. Gardevoir is weak to fire... it been 3 gen and no one noticed that