PsychicDragon
Psychic and Dragon types: weaknesses, resistances and Pokémon
Psychic and Dragon Pokémon take double damage from Ice, Bug, Ghost, Dragon, Dark and Fairy moves and resist Fire, Water, Grass, Electric, Fighting and Psychic moves.
The balance is even: 6 weaknesses and 6 resistances or immunities.
Psychic moves are super effective against Fighting and Poison and not very effective against Psychic and Steel. Dragon moves are super effective against Dragon and not very effective against Steel.
To beat these Pokémon, your best pick is Ice, Bug and Ghost moves. Avoid Fire, Water, Grass and Electric moves, which deal little or no damage.
There are 2 Pokémon with this combination, such as Latias and Latios.