Gengar fainting spell

[blastois]

Player A and player B , both have 6 prize cards left. Player A knocks out player B's Gengar with fainting spell. Player B flips heads. Both players pokemon are knocked out. Thay both did not have any bench pokemon. Who wins? Does player A win or does the effect of player B's fainting spell activate before and knock out player A 1st.
Thank you in advance for your help.

 

[PokePop]

All effects and KO's are resolved before checking game state.
In this case, each player meets one win condition.
So, that creates a sudden death situation.
Each player shuffles, draws a hand and puts out one prize for a sudden death game