Acid Spray doesn't deserve a OO mention IMO. I've used it, I've theroycrafted it, it's quite frankly disappointing on every conceivable level. Too disappointing to even be mentioned. Mollux has 4MSS as it is; it doesn't have the slot to dick around with Acid Spray. Poison is a bad attacking type, Acid Spray is a worse attack, 40 BP won't get you far, and it doesn't have the speed to abuse the SpDef drop, nor would swapping in another mon be of any real help when the opponent can also swap out and undo that work. Plus, c'mon, with that turn you could've gone for a burn, recovered HP, set up rocks, spin, all sorts of noise.
True, should probably mention that. It has a great level of firepower for a defensive mon.
Also that might be useful to note, but seems more like a bit of trivia.