[quote=@Evanist]
I know that... I though of it like ok. Cause seriously... how will eevee hit any ghost types?

That is why I think it would be ok.
[/quote]

Bite can super-effect Ghost-types / Psychic-types as well. It's just that the 20 extra PP in Shadow Ball would do a lot more damage on super-effects, around 50% more, not to mention that Sp. Def decrease. Hey, Shadow Ball is considered one of the strongest Ghost-type moves in-game. :P