Yeah haha, that happened to me yesterday too, and that isn't how it went down. Tapu Bulu with 30hp left attacked into shell trap and knocked out Turtonator with Tapu wilderness. Tapu Bulu turned sideways to show it was knocked out, then the healing kicked in and it came back to life with full hp. Is that a bug?
I see bug.
As part of the order of events, based on the above mentioned tools not damaging...
Tapu Bulu hits GX for 150, KOs Turtonator, then place its effect, full healing. After that, even if Turtonator is KOed, place 8 damage counters on Bulu. So the Shell trap still acting even if Turtonator is not there anymore. But only if, as stated in Turtonator attack, the Attacking pokémon is still there Not in PLB Donphan, not in DEX Accelgor... but Yes on Tapu bulu.
Imo should place the 8 damage counters on Bulu after full healing, and also should place it on M Pidgeot because if can do it from discard (even if KOed) retreating Turto to bench should not avoid the Shell trap effect either.
But it depends on events order.
Bulu damage 150, full healing, Turto KO, put counters. => Bulu stands with 8 counters.
Bulu damage 150, Turto KO, Bulu full healing, Turto put counters => Bulu stands with 8 counters
Bulu damage 150, Turto KO. Then place 8 counters = Bulu is KOed. No possibility of healing as is KOed.
Bulu damage 150, Turto KO. Then place 8 counters, then Bulu heals, then Bulu KO... wait, he healed in between counters and KO and last was healing so stay full heal.
To me, logic is first,
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