sapphire wonderlocke go
If you do end up doing a wonderlocke, from experience, do it without exp. share because they'll gain more exp since they're not yours (and with exp share on you'll be too leveled up for the game to be fun anymore), but turn it on when you have to grind (if you feel like it). I can't tell you how long it took me to grind w/o exp. share towards end game (training 5 lv. 30s to about 55 is not easy, especially when they die first battle). A suggestion for Xerneas if you don't plan to wondertrade it is defeat 1st then catch it.