My take: I think part of the reason Link does so good in this MU is that he gets to mess up Peach's float practically for free, with boomerang being a headache for her while we also have a great fullhop nair mid-float (gutsy), a bomb from a good angle and fullhop, or a shorthop uair/bomb straight up underneath her to mess up her landings. At least, as someone who also plays a bit of Falco (rarely as of now), being able to just throw the rang and hit her out of float is incredibly satisfying and makes it feel much easier to rush in and apply pressure (or sit back and throw more stuff) since she'll get far less float-cancelled aerials on my shield. I also think that Link and YL actually do about the same here - they each limit Peach's mobility, but fighting Peach head-on doesn't feel too scary to me (this is most likely the main reason why I think this). If YL can't shieldgrab dsmash then I definitely think Link does way better, but he probably can and I just don't know YL well. I do like up+B OoS as a punish to Peach (most notable when she takes you to FoD, which will likely happen in a Bo5 if she wins on DL and DSR is in play), and it can also edgeguard parasol (I think this is real but hard to do - if she can always avoid this, then then reason goes away, but I think a perfectly spaced/timed up+b is unavoidable, and all she can do is mix up fall speeds to try to mess up your timing). Because of the killzones on FoD and Link's up+b OoS being so much stronger than YL, PLUS the stage is kind of small so it's not like YL has that many places to run anyway, I would guess that even if YL does better than Link against Peach in general, they each do about as well (or Link does better) at least on Fountain. As a side note, the extra weight of Link also means he survives fthrow and fair longer against Peach - not to Captain Falcon levels, but better than YL for sure, and that seems relevant to me as well.
I know for me this is stage choice best to worst, but not everyone probably. I consider not only the Peach MU, but also the chances of playing not-Peach on the stage, based on strong stages for other characters:
- PS: Lots of space to camp Peach, and small blastzones for your two best KO moves, while medium blastzones give you decent survivability, but don't remove spin attack KOs from the equation. [pocket spacie risk, but I don't think Fox actually does that well relative to other stages vs Link here, and you have the platforms to help deal with Falco lasers].
- FD: Juggles all day, rather easy recovery, kill moves off all sides seem fine (though dair is still best). (how does she land from uair strings here...? Besides me screwing up of course.) [pocket Falco/Sheik risk, though I think Fox isn't much of a problem here, relative to other stages - and if you can cope with needles and lasers really well (something I'm working on), the pocket X risk seems much less.]
- YS/BF: Good neutral stage in general, got platforms for juggles and maybe early KOs off the top (But she likely doesn't get those unless you get usmashed), can also KO off the side. (for me, the difference is surprisingly negligible. BF is basically just a bigger Yoshi's - I don't usually have issues tethering, and if the Peach has me feeling cramped and wanting platforms (never happened before) I'll take her to BF over YS if I can't go PS and want platforms, but otherwise it's killzones that generally make the difference here - however, I also just like BF in general and for spacies, so the random pocket spacie feels less problematic here [even though most pocket spacies who main Peach aren't usually that dangerous] so it's about a wash to me - very slight edge to YS only because killzones and I don't mind YS for spacies, but if you hate YS for spacies and want room, BF is a much safer CP in my opinion.)
- DL: You live forever, so does she. Lots of room to roam and chuck stuff. If YL does better than Link in this MU on any stage, it's almost certainly this one, since his speed could make him ever harder to chase down (though Link still lives longer than YL here). (generally her counterpick, though if you fear the random pocket spacie, taking her here will usually ensure she doesn't bring it out for the game - Jiggs may come out, but that doesn't bother me much... however if she loses here, she might bring the spacie out game 2 or 3, so...) [might also be pocket Sheik risk but I like DL over FoD against Sheik which is why I ban FoD instead].
- FoD [I ban this stage in Bo3]: Small horizontal but high killzones means spin attack by the edge seems a better (or equally good relative to dair) KO move. Nerfing your best KO move but not hers (fair/fthrow) is not the greatest idea, and you have less space to pressure. YS seems better in almost every sense [since Randall will likely aid your recovery far more than hers, that's just an extra bonus to YS]. [also feels like a pocket Sheik risk]
I generally agree with SAUS about Link compared to YL in top tier MUs - I might say more on that later (or not).