I would say to work on the changes to the IV/EV system should be the first thing on the list. Let Serebii sort out all the new moves and abilities and crap, ALL of that should be on his site by day 3 of the release. However, if we have a brand-new IV and EV system in place we DEFINATELY should be sorting that out first.
EDIT: Forgot about BST's, those should come before the IV/EV system. But still, leave the new moves and all that to Serebii, where new pokemon/moves/abilities are likely the top priority.
EDIT: Forgot about BST's, those should come before the IV/EV system. But still, leave the new moves and all that to Serebii, where new pokemon/moves/abilities are likely the top priority.