So, considering Bisharp's attack, shall we hash out tertiary types? This is what I was thinking:
Bisharp: Steel/Dark/Fighting
Breloom: Grass/Fighting/Poison
Medicham: Psychic/Fighting
Masquerain: Bug/Flying/Water
Froslass: Ice/Ghost
Shiftry: Grass/Dark/Fighting
Jumpluff: Grass/Flying
Ninetales: Fire/Psychic/Ghost

And I was considering yours:
Spiritomb: Ghost/Dark/Rock
Gengar: Ghost/Poison
Drifblim: Ghost/Flying
Dusknoir: Ghost/Dark/Fighting
Froslass: Ghost/Ice
Golurk: Ghost/Ground/Fighting
Chandelure: Ghost/Fire/Dark
Glaceon: Ice (sub Ghost?....so not actually Ghost but shares some of its characteristics with it...maybe???)