>>48618719My Hatterene's not actually trick room, I use her outside of it (and in singles over doubles). Despite what you might expect, she's still really, really good in singles even outside of trick room. I've talked about my competitive experience before (some of those posts were probably by me to be honest), but I'm using a Calm Mind set with Psyshock/MF/Draining Kiss
and just enough speed evs to speedcreep Toxapex so it can't haze her boosts away before she tears it a new one. It's fun as heck to use.
Fittingly enough, one of the best partners Hatterene can have when used like this in all my experience is Grimmsnarl, but you'll also need at least a couple of things that can also get rid of Heatran for her.