They were clearly here to help out pro-artifact mechanics, such as affinity for artifacts
When it dies, you get to draft a witch themed card or a curse
Take advantage of Dusclops or Dusknoirs Cursed Blast Abilities, which drop either 5 or 13 damage counters on 1 of your opponents Pokmon, to either take multiple knockouts in a turn or to setup the numbers on a bigger knockout the same turn
The most impactful card introduced by XY was Muscle Band, which boosted the damage of all Pokmon's attacks by 20
Pikachu V Union Pikachu V Union has card art that's stuffed to the brim full of the Lightning-type Pokmon
Even if they somehow managed to take four Prizes at that point and damaged your Roaring Moon such that using Frenzied Gouging would cause a tiebreaker game, thats basically a win for you as youll be able to take the first Prize anyway