Why not the other giratina, the fat one with too many legs? That one is almost useless in Ubers now and I doubt it would be any good in OU. No real recovery, plenty of checks and counters, would only really benefit balance teams that need a really bulky defogger, but then it's weak Knock Off (best attack in the game), as well as other common moves like Moonblast, and Ice Beam. It would basically be a Tapu Lele that can spinblock, poorly I might add. Lele and Mega Sableye do everything it does better. Sableye would even do calm Mind sets better.
And its offenses are kinda underwhelming, Z-moves wouldn't make it broken like Reshiram and Palkia or other losers from the bottom of Ubers.
