Psychic
Flying and Psychic types: weaknesses, resistances and Pokémon
Flying and Psychic Pokémon take double damage from Electric, Ice, Rock, Ghost and Dark moves, resist Fighting, Grass and Psychic moves and are immune to Ground moves.
The balance is even: 5 weaknesses and 4 resistances or immunities.
Flying moves are super effective against Grass, Fighting and Bug and not very effective against Electric, Rock and Steel. Psychic moves are super effective against Fighting and Poison and not very effective against Psychic and Steel.
To beat these Pokémon, your best pick is Electric, Ice and Rock moves. Avoid Fighting, Grass, Psychic and Ground moves, which deal little or no damage.
There are 6 Pokémon with this combination, such as Natu, Xatu, Lugia and Woobat.