Saying does not equal showing or demonstrating. Claims are cheap and that's all you have right now. Try to do like I did and find some data at least. Show me a graph like I did, or give me an example, or something.
You just pulled the 100% chance rating criterion out of nowhere, and your desire not to check the thread is irrelevant to the argument. Moreover, if you really don't want to check that thread all over again, just don't; there are plenty of examples of people hoping despite the evidence (or lack of it). For instance, I mentioned politics and religion, didn't I?
Whatever. Those ratings are just one illustration out of many. Don't get too stuck on that thread, or on anything for that matter. You can even claim that I have chosen a bad example; it changes nothing at all to the argument itself.
Here's an article pertaining to the subject at hand.
... First off, "the game as a whole is lacking in villains" could also be used as an argument to support K. Rool, and the "lack of heavyweights" is important (We've got only three of these: Bowser, Ganondorf and Dedede, all three being villains and just as important).
Please also note that K. Rool has kind of a priority over King Boo:
Villain from a sub-series whose protagonist is the very first enemy of the mascot of Nintendo > Villain from another sub-series of the same universe (and whose protagonist isn't as important)
See what I did there? The worth of a character is in the eye of the beholder; let's leave it at that.
So King Boo, if he got in SSB, could be a heavyweight... or he could get the Rosalina treatment and up being light as hell. Who knows?