The main issue against Sheik is how safe she is compared to the rest of the cast kind of like how the complaint to Diddy was how much reward he got off with his previously frame 3, kill move Uair, and the complaint also goes to how much reward Luigi gets off of just D-throw. For me, how far and how strong Rosalina's aerials and Luma is would be a complaint. Diddy's been toned down (severely), but not Luigi or Rosalina while some characters are left as is like Sheik and Fox. Captain Falcon just got an Uair tweak which is whatever since it wasn't an insane move, but it was a powerful too for Captain Falcon. What about Link's jab cancel or Fox's? Link's to me is a major and unnecessary nerf while Fox's isn't that bad. It's the strengths between the two where I would advocate for Link's to be nerfed, but not like his. Link's much stronger than Fox, but like Fox, neither of them actually guarantee anything from jab cancel. It's not a 100% thing, but more of a 90% or 80% where there's room for error and room for the opponent to get out. You can get out of either of theirs, but people exploded on Link's. Seriously, folks, WTF? CPUs are for the lack of a better word: morons, and in training mode, they're nothing more than punching bags. Someone will find a way to DI, SDI, or counter it and obviously, an idiot constantly fishing for jab cancels is going to get punished. One Puerto Rican Fox player fished for jab cancels and decided it'd be a great idea to try and infinite a Triple D player who ended up grab resetting the moron after he failed the "infinite". Fox and Link's jab cancels were nowhere near the level of massive rewards Luigi gets from D-throw or Diddy got from pre-patches Uair. Link's could have easily had knockback and hit angle changes with some minor IASA changes and it would have been a strong tool for Link while not being able to pseudo-infinite people.
Anyway, back to the whole complaints thing. There should be buffs and nerfs to all characters. Sheik's safety is a uniqueness to her, but maybe toning it down or making other characters safer, but not as safe as Sheik could work. Luigi getting massive rewards off of D-throw is his schtick, but main lowering damage or increasing knockback could lessen the whole 40% off of one grab that few characters can ever hope for from bad DI. One case in this is Falco who was both nerfed and buffed in a way where nerfs happened to change how he functions and came out as buffs. As of right now, only Uair was radically changed with it losing its early kill potential to being a stronger, faster combo tool. Uair was good, but it's better now. Take some other character like perhaps Zelda who could have massive changes to Ftilt that turns it into a powerful spacing tool and maybe they could make it a projectile nullifier move. This assumes balance patches will happen.
I mean, let's assume that Fox, Ness, Mario, Peach, Rosalina, Yoshi, and Sheik are "perfected" characters who have some things there that could be tweaked like how Captain Falcon got his Uair tweaked, but that means there are other imperfect characters like Ike, Mewtwo, Falco, Zelda, Link, and Samus. There's a possibility they could be altered to be much better and contend better. So there's a group of characters that function well (in any mode and any situation) and then there's a group that functions, but not as well. It's like when you look at Fox in all of the games, he's always done well and never dropped severely like some characters who were heavily affected by the engine or numbers changes that can wreck them. Wolf's another example where only oversights to his design and the game itself held him back. Falco is notable for being a game exploiter as in Melee and Brawl, he succeeded by breaking the system and basically playing dirty and "cheating". Removing that basically exposes Falco to the fraud of a character he is who relied severely on game exploits and broken options. Now, with how players are viewing him and the developers noting that, they can actually give Falco a legitimate play style. Captain Falcon was also heavily affected the game's design, but the fact his game plan does rely on free movement, in Brawl, the chance of tripping does hurt his free movement philosophy. Then you have characters like Zelda who never really succeeded in any (official) game regardless of engine, frame data changes, etc. Those are the characters who can be changed as people note things that could work better for her and finalize her play style.
