I could change it to just Special Energy (although in my format that would only affect DCE) ... I like the idea of "freezing" the active Pokemon out of energy. A couple of things to consider... in my format, there are no Item cards for energy discard (or acceleration for that matter). The energy acceleration and discard in the format is mostly attack based and even the ability-based acceleration ends up only being attachable to your benched Pokemon anyway. Also, as a stadium, it's not all that tricky to get out of the effect, although that obviously could be only a short-term solution depending how the stadium war goes. Personally, I completely agree that it would be OP in the current TCG format, but I think, given that it is a standalone format and the card only affects Active Pokemon for each player, it is tough to abuse it in a particularly overpowered way.
All that said, though, I did have a bit of concern about Frozen Peak and Dark Cave (I nerfed Dark Cave a little bit before I posted it - it used to affect all Trainers - I changed it so that you can play your counter-stadium without discarding a card) and I am open to changing it a bit.