The only nerfs Fox has are the lasers dealing less damage the farther they travel, and no invincibility on Shine. And the waveshine infinite being removed.
No, I realize these are the only specific nerfs
to the character. And to somebody else's argument, the invincibility on shine lent a LOT to his edgeguarding.
The only nerf I would add to this is that his Firefox slightly curves, as a leftover from Brawl. This is a negative change for his recovery and the angles he can use.
What I'm saying is that he has received indirect nerfs from the physics system and changes to other characters. Note that I'm not only saying that the other characters have gotten better, relative to Fox... although that is true. I'm mainly saying that many of the characters have had their properties changed, such as gravity/floatiness, crouch-cancel properties, super-armor, etc, which has a HUGE impact on which combos work now, and which just don't...
Whereas in Melee, the Nair > utilt continuation was quite good and led to a lot of options... it just doesn't work on a lot of characters now, because they are able to jump out of it sooner, before any continuation. It's really that kind of thing, where the stupid Fox stuff from Melee doesn't all work in this game, so he has a much harder time against a much larger number of matchups.
His edgeguarding has been slightly nerfed by the shine invincibility removal, his combos have been slightly nerfed against a number of characters, and his recovery has been slightly nerfed in the number of angling options he has. This isn't much, except most of the rest of the cast has gotten HUGE buffs... So whereas Fox was barely the best character in Melee, he had a number of 6-4/7-3 matchups against the low-tiers, which have now been made mostly even, or even disadvantageous.
I just have trouble believing he's actually top tier now... high, definitely, but not top. All this is just my opinion, though.