Not all of them, no! There are other Dark types yeah, but there's all kinds of Pokemon with different abilities and powers. Zorua is kinda unique with his illusions, course they'll be stronger whenever he evolves.

[but cute, is he? zorua squirms out of kyouhei's arms and intends to jump into her's! because he would definitely like some pets.] Heh well since you've met Zorua, I should introduce myself too! I'm Kyouhei, I'm a Pokemon Trainer.