So, I've been battling Byron in Pearl, and my Luxray has Bite, I used Bite on it, and it says that it's 'not very effective'. The Bastiodon already had a Chesto Berry, so I'm pretty curious how bit is not very effective.
That's all. SeeYaLater!
In gen 4 dark type moves were not very effective against steel types. Source: Learning it the hard way