On the topic of Mario, I think he has a slightly better MU against Pac-Man than we do against him. And there's one reason for that: Mario's Cape. His Cape makes us HAVE to approach as we can't just spam him with fruit or a hydrant until he screws up and makes a mistake. Pac is versatile, but with going against a character with a reflector and one with good frame data, it's super hard for us to get it. Its definitely not unwinnable, but its difficult. I'd say a good 7:3 in Mario's favor.
I'd go 55:45 Mario's favor at most. I've played the MU from both sides, so I think I've got a decent idea of what goes on.
Mario's cape shouldn't force Pac Man to approach any more than a % deficit does. Cape is a good reflector, but it doesn't invalidate fruits or hydrant. The reflection window is small enough that Pac Man can still nail Mario with fruits if he predicts the cape, and if Pac Man reads a cape attempt, he can punish accordingly with an aerial, roll -> something, or wait out the cape and then run up and grab. That being said, Pac Man does have to be much more careful in using fruits because the reflection threat is real.
As Mario, I wouldn't sit back and let Pac Man get keys because they make standing, short hop, and full hop fireballs unsafe. I can't fireball camp him either because Pac Man can use his side B pellet to block the fireball(s) and heal himself, or shield himself with the hydrant and stand on or behind it. I also don't want to let him set up trampolines because they force me airborne when I do approach. While Mario doesn't necessarily mind being in the air, forcing him airborne frees up Pac Man from having to deal with his absurd ground attack speed somewhat, and Mario can't grab him while if he's coming from the air. If Mario jumps over the trampoline while facing Pac Man, Bair and Fair are pretty great for poking him for doing so, and if does anything over a SH, Uair will beat anything he has coming down.
The main problem in this MU for Pac Man is Mario's CQC game. With his Mario's great frame data and Pac Man's atrocious grab, the latter's best option if Mario gets in is to shield because majority of Mario's moves are faster and have lower commitment. Pac Man's smashes do have more range, but they are a hard commitment, and he gets punished hard if they get read. Mario on the other hand can jab, Ftilt, Dtilt, grab, SH bair, and much more without much fear of repercussions if he spaces properly (Mario does have to respect Nair and up B OOS, but they become significantly less threatening if he properly spaces his attacks).
As far as offstage goes, if Pac Man doesn't devote any of his offstage time to charging fruit, I don't see Mario gimping him ever. Side B covers a large distance, up B does too and makes Pac Man immune to meteors, and in general he's a floaty character that doesn't have to stress too much about returning.
If Mario saves his DJ and recovers low, I don't see Pac Man gimping him very often either, but he will be susceptible to the hydrant + trampoline ledge combo, which I forsee Mario having a difficult time getting around safely (but then again, who doesn't?)
Pac Man has to be careful with the hydrant in this one. He can use it to keep Mario honest during combo attempts, but cape can reflect it up back at him and it still hits. Mario can also launch it quite easily and quickly, but it can still be effective for messing with his approach attempts.
I strongly disagree with this. Pac-man can still fake out mario's cape. I never have trouble fighting him in this match up as long as I play safe against him and don't try to camp him out. Our close range game is great enough to combat his (especially on the ground where we are superior to him in range.) and we still have the trampoline to mess up his approach and we gimp him HARD. His cape doesn't fully stop our projectile game, we just have to play smarter.
I would disagree with Pac Man's CQC being good enough to compete. Between his 2 frame jab, 5 frame Dsmash, Usmash, and grab, I think we're at a clear disadvantage if Mario is close but not right on top of us.
I'd disagree with gimping Mario hard too. If he recovers low and saves his DJ, he's not that easy for Pac Man to gimp.