Toon's character attributes got generally nerfed coming from Brawl to smash 4, but because of the mechanics of the game itself, he ended up doing better overall in the new meta.
Off the top of my head:
Bair got a huge speed reduction as it used to combo into itself, be used twice in a SH, and have very little landing lag. It got a horizontal range buff but a vertical range nerf.
Nair got a significant range reduction (it used to be one of his primary spacing tools), it got an overall speed nerf (you used to be able to DJ out of a SH Nair), and it used to be a kill option.
Dair lost it's pogo and can no long reliably be used for recovery as a Dair recovery stall (which used to be one of my personal favourite things to do).
Zair got more range but it also received end-lag where previously there was none, significantly reducing it's use as a spacing tool overall. Also Zair while holding a Bomb now gives you airdodge landing lag, making that useless too.
You used to be able to Z-drop bombs without Zair coming out without needing to do anything special, and it used to be easier to Z-drop them on the ground without having them explode.
You used to be able to F-smash while holding a Bomb.
Many of his attacks got a reduced damage output including his projectiles.
Bombs got a buff of not hurting you when the explosion is caused by an enemy hurtbox, but they took away the invincibomb (airdodging then z-dropping the bomb immediately after while keeping the airdodge) which used to be one of the most significant AT's Toon had.
Arrows can no longer be quickdrawn (which was an AT that allowed you to cut out all of the startup lag when used just before landing).
The vertical height gained by his DJ and his Aerial Up-B was significantly reduced.
Dash attack and D-smash used to have low knockback angles that set up for gimps, and now their angles don't really do much.
Some notable buffs were given to the speed of his ground movement, the length of the horizontal Tether range, U-smash having a late hitbox that can still kill, significantly faster rolls, significantly reduced boomerang catch-lag, F-smash that actually connects reliably, overall faster U-tilt, overall faster grabs and a kill-throw.
The rest of the significant buffs came indirectly from the game itself due to e.g. the ledge mechanics, the increased amount of hitstun, and the lack of Brawl Meta Knight.