I've used Erufuun, and I can safely say you're underestimating it. Poor attack doesn't matter, as most Erufuun I've seen (including mine) run NO attacking moves. Likewise, poor defenses are patched up somewhat by Max investment Defense, and almost completly bypassed by MH Substitute. Erufuun can cause limitless mind games- If you get a Sub up, get a turn without it breaking, and your opponent is out of grass-types, they'll be hard pressed to stop Lefties+Sub+Leech Seed. Nattetori is Erufuun's absolute bane, however. Well, for the most part. If he comes out while you're behind a sub, you can Taunt as he breaks your sub (or doesn't, which is even better for you), then procced to do as you wish. If you're wondering what I run, Substitute/Leech Seed/Encore/Taunt is amazing. Hell, I've even outlasted Shadow Tag Chandelure with it.Erufuun: Shit defences, poor attack, and walled by grass types (no U-turn doesn't count)
And that's just Erufuun. Sableye gets priority RECOVER. If I'm not drastically mistaken, I think Sub/Recover/Will-o-wisp/Taunt is the most common Sableye set?
Oh, yeah. Don't forget that Voltos gets MH, too. And the pure-flying genie too, I'm pretty sure.