If I use Cofagrigus' "Six Feet Under" Ability and Cofagrigus is either my last Pokemon in play and/or is my opponent's last prize, but the three damage counters placed onto my opponent's Pokemon allow me to KO their last Pokemon and/or take my last prize, what happens next?
If both players arrived at a win condition at the same time but one player has more win conditions than the other (like KO'ing the last Pokemon AND taking their sixth prize), the player with the most win conditions met wins the game. However, if both players have the same number of win conditions, the game is declared a Draw and a one-prize Sudden Death game takes place to determine the winner.
Six Feet Under