Hikari Tokoyami
Don't think I recall them changing it from a 80% to a 60%... but the event wasn't that hard though it was boring.
I believe they changed it on the very last day (there was an announcement that they were making it easier, but I had already gotten the items, so I didn't bother to see how they did so).
That Chicken Yodel song was definitely one of the absolute worst songs I've ever heard. (And I was around for disco...)