The only type combination (of one or two types) that isn't neutral to at least one of them is normal ghost.
Explanation: In order to resist or be immune to ghost, a Pokemon must be either normal or dark type. They're both weak to fighting, so a type combination like normal flying would take neutral damage from fighting attacks. In order to be either normal or dark type AND be resistant or immune to fighting attacks, a Pokemon must be ghost type. A ghost dark Pokemon takes neutral damage from ghost attacks. Therefore, the above statement.
