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Well this grew.
Regarding Yveltal, the Mascot Legendary of Pokemon Y:
Confirmed Dark/Flying(as if there was any doubt).
Confirmed has Dark Aura as ability.
"When its life comes to and end, it absorbs the life energy of every living thing and turns into a cocoon once more."...
So, I'm currently battling my way through Pokemon Y and I thought I might help the community along by adding some info, but got directed here by the Bulbapedia source since editing isn't allowed at the moment(I can understand why). Hence here are some requests for editing that I have experienced...