Rosalina main here.
I'm really surprised to see that you guys think Rosalina is negative (and significantly so, at 40:60) when both the Rosalina board and myself think he's her worst matchup.
Why do you guys think that?
With customs it might be true, but I really can't see Rosalina being 60:40 against Yoshi without them. That is a ridiculous notion.
Rosalina gets kills in a lot of different ways, having one of the most diverse movesets in terms of killing options. Yoshi shuts almost all of these down. Usmash and Fsmash are very difficult to land because virtually everything Yoshi does is safe. There's really no punish game outside of grabs, which are very risky at high percents because a Yoshi player can down b without much risk at all and instantly kill a Rosalina attempting to grab.
The big aerial killers are Uair and Dair. Any time Rosalina could possibly land a Luma Dair, Yoshi is either shielding or offstage in his DJ or egging Rosalina and the Luma and knocking them out of that move. Uair is similarly difficult, because Yoshi's air speed is so amazing he can simply flee offstage and start shooting eggs. Rosalina is of course not spiking Yoshi any time soon. Which brings me to my next point:
Yoshi's recovery is virtually ungimpable thanks to his eggs. They stop every single attempt at a punish due to their large hitbox and massive amounts of hitstun. The eggs are bad for her in neutral as well because of said hitstun and the fact that they knock Rosalina quite far into the air as well as the Luma away. Rosalina never wants to be in the air except by her own choosing, because she is defenseless, takes forever to hit the ground, is lumaless, and dies early to Yoshi's usmash. As for punishing them off stage, it might be possible with an amazingly timed gravity pull, but Yoshi just fires those things so fast and if Rosalina so much as looks at them funny, her massive hurtbox insures she gets hit and knocked into the air away from Yoshi.
DJ is also very difficult to gimp, but unlike the eggs it's actually possible with a grab or well-spaced smash. Not gonna comment on it much.
This leaves the Nair and the Jab, which are definitely reliable but don't kill until like 160% due to how heavy Yoshi is. Yoshi is killing Rosalina at about 120 in the worst case scenario.
Yoshi's killers, on the other hand, are very diverse here. Down B parries grabs and instantly kills Rosalina at about 90-120, depending on stage. Fair is the one spike in the game Rosalina actually has to respect, because if challenged it GameStop trades with her own Fair. Usmash is incredibly fast with massive range and Yoshi can slide into it without much fear of a punish because worst comes to worst, he gets grabbed, if that.
Uair is also a fantastic kill move, but killing Rosalina with it isn't much different than killing most other characters, so I won't touch on it much. I will mention, however, that it can't be challenged because it is backed by DJ armor. Not that I would usually, but the option is definitely desirable in many cases.
Yoshi wins neutral with his eggs. Yes, Rosalina can GP them, but that doesn't force Yoshi to approach. Rosalina has one approach in her dash attack (because it ducks under the eggs' trajectory) whereas Yoshi has several (Standard B, Nair, Dair, and especially Fair). Fair hit and runs seem pretty staple here. They are scary and do quite a bit of damage. Nair outprioritizes almost everything. Standard B is a mixup against shields. SH Dair is quite possibly the nastiest, because it's only punish outside of a grab is Usmash before it lands, but that rarely, if ever, happens because Dair hits Rosalina before the hitbox reaches Yoshi (or before it even comes out, sometimes). It also breaks shields.
Rosalina's damage racking moves are rendered a lot less useful against Yoshi. I won't touch too much on them but because he's floaty he's hard to combo and can get away easily. But he's heavy, like Samus, so there is a huge need to get his percentage up there. Of particular note is his Nair: it's nasty for escaping the jab combo, because it insures that Rosalina only gets 8 or 9 damage (as opposed to say, 20, like with most chars). If Yoshi is too high during the start of the jab, he can punish Rosalina before she finishes as well.
I could keep going on but I feel like I've scratched the surface enough and will wait for a response first. But this is really an awful matchup for Rosalina. Almost all of her kill options are shut down and it's difficult to rack up damage on Yoshi due to how hard he is punish and how floaty he is, and in contrast he gets free reign Yoshi'ing all over the place.
Edit: Also, besides apparently Rosalina, who do you think Yoshi's worst matchups are against? Certainly you guys have played enough of him to know that, even if the matchup chart isn't completely (or even halfway) filled out.
