I think this is a bug. I have always had this issue. Every year, I check to see if anyone is still talking about it. I've gotten well of 20 KO's without dying and still get failure. I've heard people theorize that it's actually points (as in bonus points), and not the number of stocks you take, but I've also debunked that. Not sure why some games result in this issue. However, watching other people play this event on youtube and succeed after KO'ing only 2 or 3 times, I'm convinced it's a bug. At one point, a long time ago, I did manage to beat it, but it seemed completely random after a string of "Failure" attempts. I just wish I still had that memory card.