Normal/Ghost: Opossum Pokemon, possibly the evolved form of the generic normal type at the beginning of the game like Raticate/Furret/Linoone/Bibarel/Watchog. Normal/Ghost because Opossums are known for playing dead.
Poison/Steel: Garbodor evolution that's based on a dumpster.
Dragon/Rock: Druddigon evolution based on a Gargoyle.
Steel/Ghost: Could be an evolution for Golurk. For even more mileage give it levitate and it'll only have 1 weakness and 4 immunities.
Bug/Dragon: A dragonfly Pokemon, easy.
Poison/Fire: A Pokemon based on smoke and explosions.