Finding those pokemon that are good against Ghost / Fighting are pretty hard. Fortunately, a number of pokemon hit Ghost / Fighting neutral, especially all of the fairies. Unfortunately, the premier user of Ghost / Fighting is Gengar, who has easy access to STAB Sludge Bomb to own all Fairies. Without Sludge Bomb, I'm inclinded to think that Togekiss does well against the Ghost / Fighting type. 4x Resist Fighting, and it can be fairly bulky to resist Ghost. With perfect type coverage, it is impossible to expect anything better than that.
Ground Ice is only resisted by Water/Bug, and Ice/Bug, and Bronzong (thanks to Levitate).
Rock Ground is resisted by Earth/Grass and Fighting/Grass. Breloom and Torterra are the `mons to go.
Flying Ground is resisted by Electric/Flying, Steel/Flying, and Rock/Flying. (and of course, Levitate Bronzong / Levitate Rotom-W).
Fairy Ground is resisted by Poison/Flying, Steel/Flying, and Fire/Flying. (And once again, Levitate Bronzong)
Fairy Dark starts getting interesting. Poison / Fairy, Steel/Fairy, and Fire/Fairy are the only resists. IE: Mawile is the only pokemon to resist Fairy/Dark. This is the one to watch out for, if you can find it on any of the new fairies, it definitely needs to be an offensive core.
Fairy Ghost is resisted by Normal / Poison, Normal / Fire, and Normal / Steel. Unless Pyroar (Normal / Fire) becomes popular, this attack combo is also pretty much unresisted by the metagame.