It’s one of the few cards that features the “Pocket Monsters Card Game” logo on the back of the card as well as the front. All teams who reached this magic number earned a prize that matched the parent-child theme: a holographic Kanghaskan Parent/Child Promo card.
Parent/Child Mega Battle tournament challenged thousands of parent-child teams to compete in a series of battles until they reached a certain number of wins. PWCC gives background on the Kanghaskan Parent/Child Promo card in its listing.
