WaterElectric
Water and Electric types: weaknesses, resistances and Pokémon
Water and Electric Pokémon take double damage from Grass and Ground moves and resist Steel, Fire, Water, Ice and Flying moves.
The balance is even: 2 weaknesses and 5 resistances or immunities.
Water moves are super effective against Fire, Ground and Rock and not very effective against Water, Grass and Dragon. Electric moves are super effective against Water and Flying and not very effective against Grass, Electric and Dragon.
To beat these Pokémon, your best pick is Grass and Ground moves. Avoid Steel, Fire, Water and Ice moves, which deal little or no damage.
There are 2 Pokémon with this combination, such as Chinchou and Lanturn.