Tossed it. Any other option for the nature? I'll switch sync and give it another go. Stupid scenes btw. >_>
I'm resetting Groudon myself at the moment. My goal is either flawless Modest or flawless HP Ice Modest.
Brave and Quiet are good natures, but they both would prefer to have a spread of 31/31/31/31/31/0-1.
Modest and Timid are both good too, since special Primal Groudon is pretty good and common.
Adamant is not so good, because a physical Groudon has to rely on an inaccurate Precipice Blades (which can't even OHKO opposing Primal Groudon since it's a spread move) and weak Fire Punch for STABs.
Brave, Quiet, Timid or Modest are your best options imo.
PS: This is all related to VGC16. The only format where a Groudon can be used and needs a pentagon.