I've only seen one or two Scizor do that, ever. I know what you're talking about, but I've never really seen that strategy go off the ground.
For my Conkeldurr, that's assuming Conkeldurr has no priority moves, which would make it next to useless except for the Bulk Up sweep.
Mamoswine is infamous for being the best Ice Shard user. You still have a potent threat, sure, but I guarantee it will go to borderline. Along that same logic, several things in UU should be in OU, since they're strong enough with Stealth Rock resistance. Its typing is still god-awful defensively, with many things able to easily kill it before it can get a shot in, hence why Ice Shard is so necessary on it.