Actually, I thought of something similar:
Yveltal@Assault Vest/Expert Belt/Dread Plate
Mild/Rash/Hasty/Naive Nature
EVs: 32 Atk 252SAtk 224 Spe
Sucker Punch
Dark Pulse
Oblivion Wing
U-Turn/Focus Blast
Here the idea is you bluff a Choice Item then catch something off guard with Yveltal's huge offenses. One notable idea is that AV patches up a -SDef Nature which in turn will help keep the bluff going (since people might be able to read an AV otherwise). EBelt and the Plate are alternatives but IMO the Vest makes for the most of what Yveltal is: a powerhouse with a lot of staying power. U-Turn is better for the bluffing, though Focus Miss is for when you lure in a TTar (moreso in OU then Ubers). My favorite concept is baiting a scarf Genesect then bashing it with a Sucker Punch (very useful with how they will be Hasty to stop other Genes from getting the +SAtk boost).
EDIT: Wanted to also mention that a +SAtk baits Specs while +Speed baits Scarf. I prefer the extra power, since most things in that range don't run +Speed natures (I did keep the speed EVs to outpace Adamant/Modest base 95s like non-mega Lucario and Kyurem).