Water and Steel types: weaknesses, resistances and Pokémon
Water and Steel Pokémon take double damage from Electric, Fighting and Ground moves, resist Ice, Steel, Normal, Water, Flying, Psychic, Bug, Rock, Dragon and Fairy moves and are immune to Poison moves.
With 11 resistances and immunities against 3 weaknesses, it is a very solid defensive combination.
Water moves are super effective against Fire, Ground and Rock and not very effective against Water, Grass and Dragon. 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 Electric, Fighting and Ground moves. Avoid Ice, Steel, Normal and Water moves, which deal little or no damage.
There is 1 Pokémon with this combination, such as Empoleon.