Water types, leaf types, and fighting types are all supereffective against a rhydon
Water and grass type moves are 4x against Rhydon. On top of that he's also 2x weak to Fighting, ground, steel and ice. On a side note. Make sure you're using special attacks.
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.
Flying and Psychic are super effective against fighting
Lightning is super effective against water. I hope this helps.
Water and grass type moves are 4x against Rhydon. On top of that he's also 2x weak to Fighting, ground, steel and ice. On a side note. Make sure you're using special attacks.
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.
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
Ground pokemon, like dugtrio and rhydon are immune to electric attacks AND are super-effective against them. Teach them earthquake (found in victory road) and you can easily sweep his team.
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.