Fainting Spell + bench switch

[badganondorf]

If I use Gliscor LV.X's Night Slash on Gengar(SF) and Knock out the Gengar and switch the Gliscor to the bench does the Fainting Spell Knock out Gliscor if heads. I suppose yes because of the errata on Gengar but asking just for a confirmation.

 

[PokePop]

http://compendium.pokegym.net/compendium-lvx.html#297

4th answer down.
Gliscor is KO'd.