Well, a few notes I can say about the Match Up between Pac-Man and Mario -
How Mario plays: What a Mario would usually do is attempt to close the distance between you and him, often using Fireballs to force you to shield, grab you, then use his amazing combo game to beat the living pellets out of you.
CQC: Mario easily beats us here, both in the air and in the ground, IF he manages to get the distance between us. His kit is generally very fast, although his attacks doesn't have too much range, so try to exploit that. Spacing Mario is the key to succeed.
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Don't bother about using the trampoline against him - His aerial mobility and attacks are better than on the ground.
I disagree with the last part because it is the perfect counter to what you said about how Mario wants to play and his CQC.
If you spam trampoline and force Mario to approach from the air, two things happen
1) His grounded CQC and grab game become null and void. This is important because grabs are how he usually begins his silliness. If you so choose, Mario will rarely grab you in this MU because he's not fast enough to punish full retreating trampolines, assuming he's on the other side of the trampoline when you start it. You might eat a fireball, but no ridiculous combo.
Shutting down his ground game is important too because his frame 2 jab, Dsmash, Usmash, and whatnot are all very annoying to deal with. You don't have to deal with these if you keep him in the air though.
2) If Mario wants to approach us, which is in his best interest, with a trampoline out, he's coming from the air. I firmly believe we have the advantage when he's approaching from the air. Mario has very poor range along with poor approach options when he's facing you. If he's facing you when he jumps in, poke him with Fair and continue doing that until he tries something else. When he jumps in with his back to you, we can contest with our own Bair, winning trades, Uair or Usmash if he doesn't short hop, or stay grounded and contest him with Utilt, pivot Fsmash, up angled Ftilt, Usmash OoS, Trampoline OoS his landing, Nair OoS, Dtilt his landing, Bell if we have one, etc. His best and only decent method to avoid getting screwed over by us OoS is to space Bair well, and if you're behind your trampoline, you can roll into to hit him, space Fsmash, or shield and punish him when he bounces.
When he's approaching from the air, he can't block obviously, which is most people's response when they feel threatened by Pac-Man.
Important to note: Mario falling into you while Dair'ing is NOT SAFE. Get good at punishing it or you'll be eating a lot of % unnecessarily.
If Mario doesn't chase you down, feel free set up whatever you want. For Fruit, you need to be smart because cape isn't much of a commitment and reflected fruits hurt. TBH, I prioritize poking Mario on his approach attempts instead of charging fruit / setting up in this MU because cape is such a good tool to get out of most setups. If you have the chance to go for fruit, I would mainly use Key to snipe him out of his jumps and cut through fireballs ; Bell as an anti air and trapper ; mix in the other ones as you see fit, but keep in mind that all of our non-piercing fruits are easily stopped by fireballs.
At high %, retreating to the ledge is very good against Mario. That way, you won't get KO'd by landing into a Usmash. For the getup situation, unless he hard reads whatever option you choose, that's enough time to set up a trampoline safely and be back at neutral.
When you are recovering, I suggest not using air time to charge fruit. If Mario catches you off guard, he can FLUDD you past the blastzone for an easy KO. Instead, drift toward the stage and take your time to recover low. Be ready to tech stage spikes as usual.
Hydrant: I strongly caution against launching hydrant at him with laggy moves because cape isn't that much of a commitment. Mario can't run through hydrants, so I would suggest leaving it as a distraction while you set up another trampoline or charge. Also be careful when dropping them defensively, as his cape will send them back up at you. Definitely abuse Hydrant traps when he is recovering though.
Mario's fireballs: at range, Mario will most likely be spamming these. If you can do so without losing steam, pellet them and heal. Otherwise, poweshield / focus on trying to punish him for throwing the fireballs. They are quite laggy.
Now when Mario gets in, things do go downhill pretty quickly. He has free combos on most of the cast, us included. Anytime you get grabbed or get hit by some stray aerial, you could be taking 20% or worse depending on what he hit you with.
Patience is key in this MU. Do not falter and begin trying to directly contest Mario in CQC. Not only are his moves faster and have less lag than ours in general, but the reward for him landing a hit or grab tends to be much greater than ours for doing the same. Your OoS game needs to be spot on, and don't be ashamed to let the games go to time. Do not play Mario's game.
Don't let wifi discourage you from this MU either. It's much harder to deal with Mario's low cooldown moves when he's got some latency backing him up.
Mario's D-air is not safe on shield from what I recall. If he lands with it, you can shieldgrab- oh.
Never mind.
Yeah, I've made this mistake too many times. Get good at trampoline OoS guys, or Mario will get away with dairs for free.
You don't challenge Mario's SJP. You hit his double jump outta him. Cape is fairly risky to use without his double jump (It actually worsen his recovery distance, unless I'm doing it wrong), and his F-air isn't great to protect him, unless he is facing backwards for some reason. Either way, I don't see Marios using Cape to recover, as this completely negates his momentum, and if you snipe his double jump he is most likely not getting it back (Not LM's levels, but still...). The speed of some fruits also can surprise him.
Can't wait for Luigi vs Pac-Man discussion. Me's main is about to get rekt.
Turnaround fireball is an easy way to get Mario's back turned to you when he's recovering. If he goes low and has his back to us, I don't see us gimping him much. However, he exposes himself to ledge traps when he does this.
You are correct in that if we hit him out of his double jump, he should be dead.
Edit: Never gave a ratio. 50:50; The walls of text discussing what Pac-Man has to do in this MU vs. the 3 lines mentioning how bad things get when Mario gets in should give an idea of how the MU goes. Mario's gameplan is simple: get in a combo Pac-Man or KO him. Pac-Man needs to work on keeping Mario out of his comfort zone.