I just took a quick look at the Young Link match ups (since he's the only character I have any authority on), and I have to admit that the numbers are almost dead on (not that anyone really cares anyway). At any rate, here are my thoughts...
PEACH: It's about time that someone actually got the Young Link/Peach match up right. Anyone that still thinks Young Link counters Peach is an idiot. There are plenty of top players out there that have a decent Young Link, and (to my knowledge) none of them ever pull him out for this match up. However, I would love to see someone try to use Young Link against Armada just to see how badly it would end. The whole misconception of this match up began when people saw the Getting School'd 2 videos of Caveman beating Krazy Jones (which are now nearly 4 years old). Peach has evolved so much since then, and Young Link has not. I would say that the match up is, at worst, 60/40 in favor of Peach.
FOX: This is, in my opinion, Young Link's worst match up. While Sheik can CG Young Link from about 20-80%, this is only applicable on a few stages (none of which are Young Link's best counterpicks). Fox can camp Young Link, gimp his recovery, and combo him very easily with upairs. I have never heard of any instance in which a top level Young Link has beaten a top level Fox. Videos or it didn't happen. I think the match up is 15/85 in favor of Fox.
SHEIK: I don't think this match up is as terrible as most people believe it to be. I've had success against quality Sheik players in the past, and I watched Jash beat Tope in a tournament set at *pound* 3. Yes, it is a bad match up. Is it 15/85 bad? Nah, it's probably only 20/80 bad.
I'll probably comment on a few more of Young Link's match ups later.