Oddly enough, I have seen plenty of Giga Beamers -- Pixilate users are especially adept at the latter. Of course, unless you want them to be Fake Out bait, you can't run Specs/Band on them. Sylveon with Wish/Protect/Aromatherapy/Hyper Beam is particularly hard to deal with, basically OHKOing things left and right and supporting its team. Really, Giga Impact + Hyper Beam + Four supporters seems like a valid "archetype" to me, at least until the meta adapts to it.
Dragonite is also very useful here. It gets Inner Focus to handle Fake Out, Defog for hazard control, and Extreme Speed for sanic switching. If you're confident in your hazard control, Shedinja is useful as one of the only things actually worth switching into attacks; it even gets priority and Will-O-Wisp. On the other hand, it is Shedinja, so be careful with it.
Scolipede with no Speed Boost, Mienfoo when you could use Mienshao... what?
The duck is an interesting idea, though. I'll have to consider it.