An attack that may lower Sp.Def.
Earth Power is a Ground-type special move with a base power of 90 and an accuracy of 100%. It has a chance to lower the target's Special Defense stat. In Polished Crystal, Earth Power can be learned by various Ground-type Pokémon, providing them with a strong special attack option that can also debilitate opponents.
This is a Move Tutor move. TThe location page may have more information on how to obtain it.