DragonSteel
Dragon and Steel types: weaknesses, resistances and Pokémon
Dragon and Steel Pokémon take double damage from Fighting and Ground moves, resist Grass, Normal, Water, Electric, Flying, Psychic, Bug, Rock and Steel moves and are immune to Poison moves.
With 10 resistances and immunities against 2 weaknesses, it is a very solid defensive combination.
Dragon moves are super effective against Dragon and not very effective against Steel. Steel moves are super effective against Ice, Rock and Fairy and not very effective against Fire, Water, Electric and Steel.
To beat these Pokémon, your best pick is Fighting and Ground moves. Avoid Grass, Normal, Water and Electric moves, which deal little or no damage.
There are 3 Pokémon with this combination, such as Dialga, Duraludon and Archaludon.