Flash Impact/ Gengar Prime Question

[Alex(charm)ander]

Scenario: I have an active Luxray GL Lv. X and my opponent has an active say Crobat G for the sake of the argument and a benched Gengar Prime. I Flash Impact for KO and decide to place 30 damage on a benched Ambipom G with 30 HP left, knocking it out. Does it go to the Lost Zone if the opponent replaces the KO'd Crobat G with Gengar Prime?

KO's are taken into account before replacing KO'd Pokemon correct? So I am assuming my Ambipom G goes to the discard and my opponent takes a prize.

 

[PokePop]

Well, they'd get to take a prize anyway, even if it had gone to the Lost Zone.
But in this case, it is discarded.