She is decent, yeah, but if you make her use her no-attack move, she forfeits damage for that turn, and considering that she needs to be using it every turn because she's slow (or becomes slow), she doesn't do a whole lot of damage (though arguably that's not her role). As for the dion control file...bule already got her nerf, Gonzo. She's a negative-sum SS for her user (your opponent gets 2 more cards!), so when you know you're up against that nonsense, if you can trade until bule triggers, you actually come out ahead.
All in all, it's not the EXmerm that's broken. Bule is more than fair atm. Sage got his nerf and so did Dion (she used to be 40 HP!). At some point, people will have to suck it up and realize that Dion control is here to stay. It's the Morphling of Alteil--hard as hell to play, but once someone gets good at it, well, let them reap their rewards if they're willing to sacrifice their sanity to that extent.