If I Knock Out my opponent's Active Pokemon with Wo-Chien's "Entangling Whip" attack and take my last prize card but also discard the last cards in my deck, do I win or lose because I have no cards left in my deck?

You win. You lose if you can't draw a card at the start of your turn, but since you took your last prize the game ends before that happens.

Relevant cards

SV8_15