I don't think Fox is that great. The problem with Fox is his lack of priority compared to other characters. I've played Captain Jack countless times at OC2, and his Sheik beat my Fox most of the time we played, but I won a little over half our Sheik dittos. When Jack fights my Fox he controls spacing EXTREMELY well. He outprioritizes most of my attacks with his Fair, Bair, and even Forward Tilt (Sheik's Forward Tilt eats through Fox's Nair if spaced right). If I laser camp him then he charges needles, and shoots them to get me when I land, doing much more damage to me than I do to him. If I try to Nair him he usually short hops backwards and does Bair or Fair. He also smash DIs my up throw Uairs much of the time so he gets hardly any damage from it, and he tech chases me very well. After he down throws me, if he sees me tech roll he dash attacks in that direction, and combos me or tech chases me to death with much success. If I tech in place he does various things to mix it up, but the most common is to Jab me for just before I can attack him. If I don't Crouch Cancel this Jab, it's basically another free grab for Jack. If I DI his attacks toward the center of the stage, he often does a few tilts to a dashing Up Smash (me expecting him to Fair me off the stage like most Sheiks do, so I DI into him many times because of this)
Anyway the point is, Sheik does good on Fox on many stages. I think Fox does good on Poke Stad, FD, and Yoshis Story, while Sheik has the advantage on DL64, Battlefield, and FoD.
And no Fox does not **** Sheik it's a pretty even matchup contrary to popular belief.
While Fox doesn't have any real counters besides Falco (I don't care what you say PC Chris) he has a lot of pretty even matchups.
The top 4 characters in the tier list, Falco Fox Sheik Marth, are all within like 99% as good as each other basically. Arguing over who's better by 1% just so they can have an excuse if they lose a matchup with them by that 1% advantage being the reason they lost is stupid, but is also a big reason why the Tier list is so argued for many people.