Some Pokemon are different from normal... these pokemon are: Metallic, Ghostly, Shadow, Dark, and Shiny. (Listed most common to most rarest, normal pokemon being first of course, since normal pokemon do not have an ability. Now, each one of these pokemon has a different ability... here they are.

Normal - These pokemon are most common. They have no abilities, none. Zip. Nada.

Metallic - Cannot be effected by status, like Burn, Poison, Confusion, Sleep, and Freeze. This ability is nullified to Shadows.

Ghostly - When a Ghostly pokemon attacks, they have a chance of making the other pokemon flinch. This ability is nullified to Shadows.

Shadow - Metallic and Ghostly abilities do not effect this type, I.E Metallics can be effected by status if the Shadow pokemon has a status move, and Shadows wont flinch to a Ghostly pokemon.

Dark - Every attack that hits the opponent has 25% more power to it.

Shiny D - 25% more HP, I.E A Pokemon that normally has a max HP of 400, compared to a Shiny that has 500.