If you ask me (which you did lol), personally I would use Leftovers on Scizor and Chesto Berry on Latios. I think the benefit of Leftovers or Wise Glasses on Latios would not be higher than the benefit of Chesto-Rest in most cases.
AND... actually, if you want to boost your Special Attack, you might as well use a Dragon Fang/Plate, since Latios has only 1 attack. Boosting by 20% is better than by 10%. But yah, I'd use Chesto.
EDIT: Oh, by the way, you still haven't put in the natures for your Latios and Scizor.