PoisonRock
Poison and Rock types: weaknesses, resistances and Pokémon
Poison and Rock Pokémon take quadruple damage from Ground moves, take double damage from Water, Psychic and Steel moves and resist Poison, Normal, Fire, Flying, Bug and Fairy moves.
The balance is even: 4 weaknesses and 6 resistances or immunities.
Poison moves are super effective against Grass and Fairy and not very effective against Poison, Ground, Rock and Ghost. Rock moves are super effective against Fire, Ice, Flying and Bug and not very effective against Fighting, Ground and Steel.
To beat these Pokémon, your best pick is Ground moves. Avoid Poison, Normal, Fire and Flying moves, which deal little or no damage.
There are 3 Pokémon with this combination, such as Nihilego, Glimmet and Glimmora.