Some of these (like special rock) are ranked high because they're so damn hard to take advantage of that even pokes with that weakness can excel.Wait...
What is a special Rock move? It might be because it's 6:30 but I can't think of one.
That's what makes this data a little bit counter-intuitive. Still, useful stuff to take note of.
Flying is ranked very well, but with brave bird/drill peck on so few pokemon and air slash being a generally sub-par attack (and again, not widely distributed), there's little way to take advantage of it, and thus a lot of flying-weak pokemon able to succeed.