Is the card game just random luck?

I popped an in-training digimon with a score of 2 first, thinking id get him out the way and then counter the opponent when they take their turn. The opponent used an Ultimate with a 5 score. yet somehow my in-training won?

Is it solely type advantage that determines the winner so my in-training won because it had a type advantage or is it randomised but you have a better chance with type advantage and higher card core.