FireRock
Fire and Rock types: weaknesses, resistances and Pokémon
Fire and Rock Pokémon take quadruple damage from Water and Ground moves, take double damage from Fighting and Rock moves and resist Fire, Normal, Ice, Poison, Flying, Bug and Fairy moves.
The balance is even: 4 weaknesses and 7 resistances or immunities.
Fire moves are super effective against Grass, Ice, Bug and Steel and not very effective against Fire, Water, Rock and Dragon. 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 and Ground moves. Avoid Fire, Normal, Ice and Poison moves, which deal little or no damage.
There are 3 Pokémon with this combination, such as Magcargo, Carkol and Coalossal.