Ruling Tyranitar and Gengar?

[Elk-Dimension]

So, I'm playing a Tyraintar (SF) against a Gengar (SF). If I knock out my opponent's active Gengar with Tyranitar's "Grind," what activates first? Gengar's "Fainting Spell" or Tyrainitar's "Darkness Drive?" In other words, do I attach a Darkness energy before or after it gets knocked out by Fainting Spell?

 

[DNA]

Fainting Spell triggers first. Darkness Drive only triggers after all effects of a Poke-Power have been resolved, so only after Fainting Spell finishes its effect can you activate Darkness Drive.