In Usage Statistics of forums, there is a bug... The bug is only of Pokemon which has 2 forms where both forms have different ability... Here is an example of a Giratina-O It has only Levitate as its ability... However when we look at its usage (the place which I have highlighted), where the ability shown in usage, it shows ability "Pressure" which is ability of its other from i.e. Giratina... It happens in other Pokemon too such as Basculin-A, Giratina-O, Shaymin-S, Tornadus-T,Thundurus-T,Landorus-T,Kyurem-W,Kyurem-W where all of these have different ability than its original form... You can check their statistics photo of all together here... http://imgur.com/lp5S6hy,MlSCeOe,mpxJDPZ,IIm6x2l,ouwXrwL,g0db3aP,a2zQy8e,N3tGGeD#0
This is a minor logic issue, nothing more It isn't that big of a deal, so we'll look upon it when we don't have other things on our hands.
Just want to point out, now that Hackmons is out, the "minor issue" just expanded to a major one, as the abilities for Hackmons are typically blank.