If both groudon and kyoger both primal reversed at the same time and have same EVs and IVs for speed,so which ability take effect last.
If both have the same speed (IVs, EVs and nature) it will be a 50/50 situaion kind of like a coin toss. No way of telling which Pokemon (Primal Groudon or Primal Kyogre) will get its ability up first.
Hope I helped!
-It's a secret!
Whichever of the two primal revolves last.