One type is ground, another is water and psychic will work too! If you tell me where you are in the game and what game it is I'll tell you how to get a Pokemon to defeat it with. If it's Colosseum use espeon leave it in day-care and do a load of random battles or do Mt. battle. I know that that armaldo is hard so just a guess.
Armaldo is a Rock/Bug-type Pokémon, which makes it particularly weak to Water, Rock, Steel, Fighting, and Flying-type moves. Among these, Water-type moves are super effective against Armaldo, dealing double damage. Therefore, using a strong Water-type Pokémon or move would be an effective strategy in battle against Armaldo.
Flying and Psychic are super effective against fighting
Lightning is super effective against water. I hope this helps.
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.
One type is ground, another is water and psychic will work too! If you tell me where you are in the game and what game it is I'll tell you how to get a Pokemon to defeat it with. If it's Colosseum use espeon leave it in day-care and do a load of random battles or do Mt. battle. I know that that armaldo is hard so just a guess.
Bug Type and Fighting Type moves are super effective against it.
Rock, electric, ice, and psychic types are super effective against Crobat.
Steel is super effective against rock type pokemon.
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.