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