During the triple battle with Avatar Regigigas, the following things happened regarding status damage
-The popup for poison damage occuring (IE badly hurt by poison, brought to it's knees by poison, etc) would not display, and the pokemon would not take damage
OR
-The popup for poison damage/poison worsening would appear, but the pokemon would still not take damage.
Additionally
-Status damage from other statuses (Like Frostbite or Burn) would function properly.
-A leeched pokemon (Muk) that was switched out would have their HP display over the pokemon in the leftmost slot in the triple battle(M.Mandibuzz) whenever they took status damage as a result of Naganadel's "Inexorable" ability. The name would still display as the leftmost pokemon, and whenever their actual HP was changed (by being attacked, or healing from an item/move), their correct HP value would be displayed.
I have some footage, but my capture software can be shitty and I haven't checked it. If there's any other information that you think might be helpful, let me know.