If I used Poipole's "Knockout Reviver" attack, but then on my opponent's next turn they play Channeler, would that allow them to take a prize for KO'ing Poipole?
No, it would not. The effect of Knockout Reviver resides on Poipole, and the opponent's Channeler only clears effects on the opponent or their Pokemon.
Knockout ReviverChanneler



