Yo let's get this Gen VII party started

[Fett One]

My current status: I finally have all 18 type-based Z-Crystals (plus 3 more) and have made it to the League, but I have a team of 14 level 40 Pokemon... Which means I have reached the most annoying part of the game: grinding in order to become strong enough to face the Elite Four. What levels should my Pokemon be in order to stand a decent chance?

The elite four pokemon are between level 54-58.

[Lady Vulpix]

Thanks, but that's not exactly what I asked. Anyway, I'll try to reach level 45 and see what happens.