Ghost & Flying. I believe that's it!
Not dark or bug because although they're super-effective against Psychic, they are not-effective against Fighting. And not Psychic, because though it's super-effective against Fighting, it's not-effective against Psychic.
Chat with our AI personalities
Gallade is weak against Ghost, Flying, and Fairy-type moves. Avoid using Fighting and Rock-type moves as much as possible, for those are its resistances.
Water and Grass attacks are super effective against Onix.
super effective is bug
psychic pokemons and attacks are super effective
Rock, electric, ice, and psychic types are super effective against Crobat.