Basically, it wasn't included because CAP and Ranbats are there to draw people in and the other four were the top four by a large margin. Glitchmons also had almost no battles last month on its PS ladder. It's not like we have anything against Glitchmons, and I think it would have brought a few other players out of the woodwork, but outside of that it just doesn't have a playerbase big or active enough for OMPL. I'll keep it in mind though.
If/when IRC mini-tournaments happen, Glitchmons will probably get the first slot, if that helps!