heh, how cute. Not many Flying-types are around either, and Levitate Pokemon are pretty much non-existent other than teambuilding mistakes. However, this still seems pretty niche. You have to ask yourself what is more useful: trapping Flying-types (Lugia, Ho-Oh, mainly) or trapping Pokemon with the ability Shadow Tag? This strategy also wouldn't work well if everyone started to use Arena Trap Pokemon, although I doubt that will happen.Hmm, I wonder how viable Arena Trap is in this metagame. Yes Shadow Tag is "superior" but Arena Trap can trap other Shadow Tag Pokemon which in my experience are becoming more and more common.
The tournament that Imanalt talked about was fun. I got knocked out pretty quickly thanks to hax and a few misplay's, but Sap Sipper Shift Gear Rhydon was fun as hell. You don't care about Spore's, you lose a 4x weakness, you are physically bulkier than Giratina, you have a great Attack stat backed by a brilliant offensive typing, as well as a few other useful attributes. Rhydon has a lot of potential in Balanced Hackmons; I want to see it used more.
Another Pokemon that has potential in Balanced Hackmons is Shaymin-S. Shaymin-S is incredibly fast and quite powerful, although a bit frail. I was using a set that is very similar to common Shaymin-S sets: Sub / Roost (obvious difference) / Seed Flare / Air Slash with Serene Grace and a Life Orb attached. It probably isn't the best set, but it haxed through a bunch of people and did well even without haxing. Roost is an excellent move on Shaymin-S. It's a shame that Shaymin-S can't learn it other than in Hackmons.