ElectricDark
Electric and Dark types: weaknesses, resistances and Pokémon
Electric and Dark Pokémon take double damage from Fighting, Ground, Bug and Fairy moves, resist Electric, Flying, Ghost, Dark and Steel moves and are immune to Psychic moves.
The balance is even: 4 weaknesses and 6 resistances or immunities.
Electric moves are super effective against Water and Flying and not very effective against Grass, Electric and Dragon. Dark moves are super effective against Psychic and Ghost and not very effective against Fighting, Dark and Fairy.
To beat these Pokémon, your best pick is Fighting, Ground and Bug moves. Avoid Electric, Flying, Ghost and Dark moves, which deal little or no damage.
There is 1 Pokémon with this combination, such as Morpeko.