151 Chansey's Lucky Ability
151 Chansey's Lucky Bonus Ability causes the game to incorrectly track how many prize cards have been taken when taking more than 1 Prize Card where 1 of those cards is Chansey, evident in damage output from Charizard ex.
This seems to be related to the animation for taking prize cards, and it being interrupted by an ability. The initial animation revealing what prize cards were taken plays. (Chansey and Charmander, for example) Both cards do not enter the hand yet. The game prompts the player if they wish to use Lucky Bonus. After the ability is resolved and Chansey is on the bench, the game plays an animation putting the second Prize card initially taken (the Charmander) into the hand. Each time this animation is played, the value for "total prize cards taken" goes up.