I honestly think the dude is just !@#$ing with us. I mean, think about it; the majority of the easter eggs found within recent years is because technology has advanced enough to let every day users see the coding used in the game, and even manipulate it. When you have an entire community of fans ripping through the data on a game, odds are every secret is going to be revealed. That, and every trick in the book has been tried out. The M tank trick, a lot of details about the music, several things the weapons can do outside of their regular functions, Forte at the end of the game. We know every sprite that's been used in the game, so if there was some hidden image in them, we probably would have found it by now. The numbers in the game also have been discovered to be the release date of the first Mega Man game. As far as boss' damage goes, we already know how much damage they take from it, and even the tornado being used against the sub's second form dealing two hits worth of damage.
I mean, what else is left? Hidden areas containing life ups or tanks? That's about the best I can come up with.