ZSS<Kirby
ZSS>Wario
ZSS=Lloyd

Explanations?

All I have to say for Kirby is "Dair", It is simply Impossible to recover from a Kirby abusing dair offstage. The knockback is ridiculous and it can take out ZSS' jump easily. If ZSS doesn't jump She can't make it back to the ledge on some stages.

ZSS vs Wario: ZSS has many safe options against Wario Such as SideB, UpB and Nair. SideB can cancel shoulder and has very good combo potential. It also is a good edge guarding option forcing jump from the ledge. Wario's UpB is very easy to punish because of how slow it moves and is basically a horizontal attack.

ZSS vs Lloyd: ZSS and Lloyd are like Seviper and Zangoose imo. Both characters have good approach options and combo potential ZSS beats Lloyd in recovery however and Lloyd beats ZSS in edge guarding potential + strength.

Marth-Marth is a 0-0 matchup.

This is currently a gray area for myself. ZSS does indeed have the advantage, but with Wario Waft and Wario's weaving capabilities, coupled with ZSS's general playstyle, it doesn't seem like a terrible MU. Given how tall ZSS is, she gets comboed by Wario pretty well too.
Then again, ZSS can easily gimp Wario, keep him at bay, and has better attributes overall. Her Jab is also a great tool vs Wario up close, cause it stuffs most of his moves, and is fast enough to poke him if he leaves even 1-2 frames free when Wario is comboing her.

yeah apart from the fact that seviper is utter s*** and zangoose is a baller

uber > ou > uu > ru > nu > pu
checks out

Would anyone be interested in seeing my opinions for all the vs Peach MUs with short explanations?

yes please

Definitely.

Cool. I'll make a word document of them and upload them here batch by batch, then give a link to the document with all of them once every MU is uploaded.

sorabee w/ the yun resources, quality contributor, 8~/10 user, mod imo

Here are the first six. Please let me know if you have questions, comments, or would like a more in depth explanation for any of these MUs.

Short Peach MU Guide: Part 1
vs Mario- 40:60. Mario’s dash and air speed makes it difficult for Peach to catch a break. Mario’s offensive game easily overtakes Peach’s, and U-smash is a good KO move for Mario. However, Peach can edgeguard Mario somewhat limited recovery and can Nair through fireballs. Turnips will also help this MU be a little more bareable and both can combo each other fairly well, Mario a little more so than Peach.

vs Link- 40:60. Link’s projectile game makes it difficult for Peach to get in. However, Peach can combo and edgeguard Link pretty easily. Link’s Dair kills extremely early (around 80ish%) and he has B-throw, Ftilt, and Uair as well. Once Peach gets in and tech chases well, Link will have it tough but in general, Link should win the Neutral and have an easier time finishing Peach off. Tbh, I don’t have too hard of a time with this MU but I heard other Peaches do so I accounted for that. For me, it’s more like 40:60 or 45:55.

vs Kirby- 65:35. Peach does pretty well vs the floaties and Kirby is no exception. Kirby doesn’t have the aerial game or neutral options to deal with Peach’s turnips, Fair, and Nair even. Turnip>Fair can kill Kirby pretty early and Kirby has to rely on well spaced Bairs and Fsmashes to finish Peach off.

vs Samus- 60:40. Another floaty MU lol. Even though Samus has the missiles to zone Peach out, Peach can throw turnips and Nair through missiles and charge shots. Once Peach gets through this, Peach can combo Samus decently because of her size mainly. Her recovery is pretty limited and can be edgeguarded with a well timed Fair. Samus also has trouble killing in general so Peach will survive for longer than she should.

vs Megaman- 55:45. This is a tough one.If Megaman camps really well with brick and crash bomb than Peach is going to have a hard time getting in. Ftilt and dash attack will also give Peach trouble coming in from the air. However, if Peach lands a solid hit and megaman is forced to recover, Peach can easily edgeguard Megaman’s Up-B. Megaman also has more kill moves than Peach.

vs Fox- 35:65. Unfortunately, Peach does not have the ground options or speed to play a defensive game versus Fox. Fox can run all over Peach and she will be powerless and get pushed into the corner. However, Peach has massive combos on Fox that can easily convert into an offstage situation, where the Fox should be easily edgeguarded with Bair or Nair vs Firefox and Nair vs Illusion. Additionally, Fox can laser camp and force Peach to approach which can be really hard since Fox has his great Nair and Bair.

while I do disagree w/ you on fox, these r good, keep em comin'

I think you might be a little heavy handed on the 65-35s. That's like the saying the matchup is almost unwinnable (these are hard counters). If that's how they are then that's all fine (I don't suggest changes), I just want to make sure that you know what the numbers mean. At last 60-40 is doable (just quite difficult).