Diancie (Quiet)
HP: 30 - 31
Att: 24 - 25
Def: 26 - 27
SpA: 30 - 31
SpD: 30 - 31
Speed: 31
This is pretty awkward..can I keep this?
What you have to ask yourself, is would you personally use it? If the answer is no, then you'll have a hard time selling it to anyone else. If the answer is yes, then keep it and play the game. At the moment these can't be traded, so what really matters is if you're satisfied with it or not. Personally, I don't think I would use anything but Timid/Modest/Naïve/Hasty, with 30+/X/29+/31/29+/31, with X being 31 if mixed or X being anything if special, but to each their own.
EDIT: My reasoning on the natures, is basically that with 50 Base HP and 110 Defense stats, it really isn't that bulky; Mega Pidgeot's defensive base stats and Diancie's both add up to 160, and you don't see anyone running anything but Modest or Timid Pidgeot. Only reason Diancie can run Naïve / Hasty is because it has 160 base attack and special attack and 110 speed.