Ghost type Pokémon.
Dark-type Pokemon are weak against Fighting, Bug, and Fairy-type attacks, unless a dual-type resists one of these types.
Lucario is a Fighting and Steel-type Pokemon, meaning that Fire, Fighting, and Ground-type attacks are its weaknesses.
Fighting type pokemon are weak against psychic attacks
Raticate is a Normal-type Pokemon, so it's weak to Fighting attacks.
It's an Electric/Steel-type Pokemon, so it's weak to Ground, Fighting, and Fire-type attacks.
Dark-type Pokemon are weak against Fighting, Bug, and Fairy-type attacks, unless a dual-type resists one of these types.
Steel type Pokemon are weak against Fire, Fighting, and Ground type attacks
Lucario is a Fighting and Steel-type Pokemon, meaning that Fire, Fighting, and Ground-type attacks are its weaknesses.
Fighting type pokemon are weak against psychic attacks
Normal Pokemon are weak against fighting Pokemon.
Rock-type Pokemon are weak against Water, Ground, Steel, Fighting and Grass-type attacks.
Ice Pokemon are weak to Fire, Fighting, and Rock type attacks.
Machop is a fighting-type Pokemon, and is therefore weak to Flying and Psychic attacks.
Raticate is a Normal-type Pokemon, so it's weak to Fighting attacks.
Fighting Pokemon are weak against Psychic types and Flying types. Ghost Pokemon are also a good choice against Fighting types since Fighting and Normal type attacks don't effect them.
It's an Electric/Steel-type Pokemon, so it's weak to Ground, Fighting, and Fire-type attacks.
Rock-type Pokemon are weak against Water, Grass, Ground, Steel, and Fighting-type attacks, which doubles the damage received from one of these types.