Theorycraft balancing time! Wooo!
My biggest issue with Sheik, when playing against her, is her "get out of jail free" card. She already has the best tools for the neutral game (or at least top 3, I've heard a couple of cases for a couple other characters.) So when you actually do make a good play and get her in disadvantage, she just. . . flops out of it. Some characters can read and bait out the Bouncing fish, but mostly by the time they can attempt to catch it, she's recovered and is back to her amazing-frame-data-and mobility neutral game. It's very frustrating to actually catch a Sheik, have her flop out, and then proceed to throw needles at her until you catch her again, and she flops out and throws more needles at you.
I guess what I'm saying is: I'd add a little bit more recovery to her Bouncing Fish on whiff. On hit, or on Shield, I'd keep it the exact same. A little bit of extra lag on whiff means when she uses it to get out of disadvantage state, if you guess which way she's flopping you'll get a little bit more frame advantage to attempt to trap her and punish. She's still a ninja, and being able to escape makes sense for her general design, but this way it's more of a 50/50 to escape. Seems pretty Ninja-like to me, you can escape as long as you're a step ahead of your opponent. And even when they guess right, they're only at a slight advantage.
Zero Suit? My biggest issue with her is that her kit seems designed for her to be an agile midrange fighter with a strong punish game, and she's got a real weakness when you can bait out her grab. People are figuring out ways around her Boost Kick which is good, but what annoys me about her design is her ludicrously fast jab. It just seems counter to the design of a mid-range character. So you've navigated past her d-d-danger-zone and are now in her face. Good, that's where you want to be against a spacing character -- either safely OUT of their range, pressuring them with projectiles, or IN their faces, stuffing them with your shorter reach but quicker moves. So if you safely navigate your way past the Zairs, blasters, grabs, and nairs. . . you get stuffed by a quick jab in the face, and are now in the d-d-danger zone again.
I like the idea of an agile mid range combo machine, but that jab just invalidates a lot of the work of safely getting in against her. She's got the mobility to get out of disadvantage well, so adding a couple more frames of startup wouldn't completely invalidate the character, it just gives her an extra blind spot for players to try and exploit. Once again, it creates avenues for smart play and guessing games instead of the flowchart I see with some ZSS players "In my face? Check. Are they trying to attack or grab me? Check. Jab." Now it's more of a "Are they in my face? Check. Are they trying to attack me? Run away and pivot grab or dodge in place and punish. Are they trying to grab me? Jab. Are they trying to wait me out and see what I do? Escape! Are they in my face trying to bait me with a dodge? Wait it out, hit them with something." It just seems to me that when you safely did get in that space, Jab was just too quick and covered too many options. It was a panic button of sorts. That's really what I want to get rid of, panic button solutions to pressure.
I'm not a top level player, truth be told I'm usually too busy streaming and hosting these days to play much. . . but when I fight a ZSS or Sheik those are things that annoy me most about the characters. I think, given those two nerfs, Sheik and ZSS would still be 1 and 2 in the game, but it gives some more options for counterplay against them. A couple of windows where you can make them sweat a bit. I don't want to take away their strengths, I just want to add a slight chink to their armour that makes sense for their design and game plan. As I said before, I want to get rid of panic button solutions to pressure, and Bouncing Fish and Jab, at least to my inexperienced eyes, seem like exactly that. They cover holes that could be found in those character's kits. Those are two weaknesses that make sense to me, for what it's worth.