The type effectiveness of bronzong varies according to his 2 abilities:
1. Levitate = Weak to fire.
2. Heat proof = Weak to ground.
But to make this simple you can say that in-game bronzong is only weak to fire, since every in-game bronzong has the ability levitate.
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.
Water and Grass attacks are super effective against Onix.
Steel is super effective against rock type pokemon.
Rock, electric, ice, and psychic types are super effective against Crobat.
super effective is bug
Flying and Psychic are super effective against fighting
Lightning is super effective against water. I hope this helps.
Brongzong are weak to either fire type or ground type moves depending on whether they have the Heatproof or Levitate special ability.
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.
Water and Grass attacks are super effective against Onix.
Bug Type and Fighting Type moves are super effective against it.
Steel is super effective against rock type pokemon.
Rock, electric, ice, and psychic types are super effective against Crobat.
super effective is bug
psychic pokemons and attacks are super effective
Bug types are super effective against Dark, Grass and Psychic (x2) in Generation II-onward. In Generation I, they were super effective against Grass, Poison and Psychic.
normal type Pokemon are not super effective against any type.