Psychic and Steel types: weaknesses, resistances and Pokémon
Psychic and Steel Pokémon take double damage from Fire, Ground, Ghost and Dark moves, resist Psychic, Normal, Grass, Ice, Flying, Rock, Dragon, Steel and Fairy moves and are immune to Poison moves.
With 10 resistances and immunities against 4 weaknesses, it is a very solid defensive combination.
Psychic moves are super effective against Fighting and Poison and not very effective against Psychic and 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 Fire, Ground and Ghost moves. Avoid Psychic, Normal, Grass and Ice moves, which deal little or no damage.
There are 8 Pokémon with this combination, such as Beldum, Metang, Metagross and Jirachi.