BugRock
Bug and Rock types: weaknesses, resistances and Pokémon
Bug and Rock Pokémon take double damage from Water, Rock and Steel moves and resist Normal and Poison moves.
The balance is even: 3 weaknesses and 2 resistances or immunities.
Bug moves are super effective against Grass, Psychic and Dark and not very effective against Fire, Fighting, Poison, Flying, Ghost, Steel and Fairy. 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 Water, Rock and Steel moves. Avoid Normal and Poison moves, which deal little or no damage.
There are 6 Pokémon with this combination, such as Shuckle, Anorith, Armaldo and Dwebble.