You do not want synchronize.
It provides: "When statused, the enemy is also statused. Can pass nature to wild Pokemon." which is useless in PVP.
While Magic bounce: "Bounces back certain non-damaging moves." which will prove more useful in PVP than sync does.
Also Early bird: "Reduces sleep time by 50%." which isen't bad. I recommend having Magic bounce though, I find it more viable with xatu if your going to use him.