Dusknoir and In Between part 2

[Kayle]

Well, although it's nice to clear up the KO checking condition timing, my actual question is still unanswered, and I'm still curious - who determines what goes first, since each players own one effect?

From my original post:

- If my opponent has Dusknoir Lv. X in play and I have an active Pokemon with 10 HP left and a Nidoqueen on my bench, which happens first - Ectoplasm's damage or Maternal Comfort's healing?

What if the Active has full HP? Does Dusknoir place a damage counter and then Nidoqueen removes it, or does Nidoqueen remove no damage counter and then Dusknoir places one? Would the Pokemon end up with 0 damage, or 1?

 

[PokePop]

It's not who owns the effect, it's who owns the Pokemon that is being affected that gets to make the choice of timing for simultaneous actions.