ElectricPoison
Electric and Poison types: weaknesses, resistances and Pokémon
Electric and Poison Pokémon take quadruple damage from Ground moves, take double damage from Psychic moves and resist Grass, Electric, Fighting, Poison, Flying, Bug, Steel and Fairy moves.
With 8 resistances and immunities against 2 weaknesses, it is a very solid defensive combination.
Electric moves are super effective against Water and Flying and not very effective against Grass, Electric and Dragon. Poison moves are super effective against Grass and Fairy and not very effective against Poison, Ground, Rock and Ghost.
To beat these Pokémon, your best pick is Ground moves. Avoid Grass, Electric, Fighting and Poison moves, which deal little or no damage.
There are 2 Pokémon with this combination, such as Toxel and Toxtricity.