dark/ ghost has no weaknesses.
bug/ steel has only one weakness and 10 resistances
dragon/ water only has a weakness to dragon
dragon/ steel has 12 resistances
normal/ psychic has only 2 weaknesses and ghost has no effect. This is the only combination of normal with another type that normal covers a weakness.
electric/ steel has 13 resistences
steel/ grass has 11 resistances and only2 weaknesses
poison/ dark has only a ground weakness
ground / water has only a grass weakness(credit to Pokemoning and mirkjani for those two)