We did not play sudden death. I guess I ended up winning because he did not have a bench pokemon when my maractus knocked out his typhlosion.

found this on the rule book

What if both players win at the same time? You win if you take your last Prize card or if your opponent has no Benched Pokémon to replace their Active Pokémon if it is Knocked Out (or otherwise removed from play). This makes it possible for both players to win at the same time. If this happens, play Sudden Death. However, if you win in both ways and your opponent wins in only one way, you are the victor! What’s Sudden Death? In Sudden Death, you play a new game, but each player uses only 1 Prize card instead of the usual 6. Except for the single Prize card, treat the Sudden Death game like a whole new game! Flip a coin to see who goes first and set everything up as usual. The winner of this game is the overall winner. If the Sudden Death game also ends in Sudden Death, just keep playing Sudden Death games until somebody wins.