Correct me if any of this is off base
Peabnut Bubber
I strongly agree with what you said about him having to avoid disadvantage to do well. When I played Tyroy, my main issue was returning to the stage and Witch Time. A big plus for MM is his weight, which gives him great survivability when you consider that he is small and pretty nimble. I've won a lot of games at my locals with the casters and my enemy thinking I was dead, but I survive and come back and boom. This is however partially offset by his weight at low percents, something like a cloud or fox vortex is gonna take MM on a bit of a longer ride than most characters suffer. This is why fox is miserable, you don't get out until you are close to dead. You can actually keep fox out alright, if he got like Diddy reward for getting in it might be close but instead he just ravages you and most of your moveset just doesn't even have stopping power vs his frame data.
But anyways, something I see about megaman that isn't true is that he barely gets reward. He gets bad reward for pellets, sure, but they aren't for damage so much as control/MU specifics / edgeguarding (pellet means you cant ledgegrab for a second, which sucks vs dair or bair). Otherwise, he gets pretty solid reward. He doesn't do Diddy damage, but for a non combo grab MM does a lot. 12% backwards. I also like the 6% (iirc) for upwards; them being directly above you is great.
Brings me to my next point. Uair. This some great stuff. We all know about the early kills, blah blah w/e. But, it gives him a nice shield pressure tool that is safe depending on their height and OoS. The mixup between tomahawk and uair on shield can make them try and OoS panic to avoid a grab, then uair hits
When uair hits, you have tons of options. If they are slower than you in the air, then you can really lay into them with uair. Uair is also absurdly good at triplats, using it rapidly (just before you land from shorthops) and well spaced means they have to go around. Clever usage and they are really suspect to either bair air to air, or a thrown metal blade on landing.
Uair is also decent at the ledge. You can cover a lot of options (heavily dependent on their hitbox size), you can cover ledgejump with less committal than most characters can, and if they get launched you have some really good chances to juggle, regrab, bair in the air, etc etc etc.
Oh quick note on shield pressure, zdrop metal blade is pretty nice for covering you against shorter characters, you can drop it such that it will smack them if they try an OoS. This should combo into bair or dashgrab, or just pellets if you don't feel like going in. Against big characters a well dropped metal blade (close to them so its falling slow) will RAVAGE their shield. Bair, being a multi hit, can add pressure and even shield poke on the later hits, though this is mostly vs heavies.
Something mega has in disadvantage that he shares with Diddy is OoS items. They are great. Something like corrin bair is usually safe, but chucking a metal blade out at them will punish at a very long range. This is very much my gameplan against ANYONE with a mediocre grab punish, I'm dash shielding everywhere and if they call me out it is alright, though someone like Cloud can turn a throw in 50 uairs and that can hurt. You have zdrop options as well, meaning you have a chance to do the infamous footstool kill if they run in and whiff something.
I find that crash bomber is heavily heavily underrated. Sure, in a neutral situation it is pretty easy to dodge or negate. So is paralyzer and DFS. Why do they shoot it then? The reward is great, and the risk is low if you space correctly. If you stick someone and they don't immediately run at me, fsmash suddenly becomes a really solid option. If they shield the CB an instant too soon so the shield starts decaying, they can be effectively trapped. Roll gets hit with fsmash because they get crash bombered into stun, if they sit in shield the decay + CB + Fsmash will cause a shield break.
I like to try and stick them when they are returning to stage, someone like corrin is easy to stick when she bairs to go further or just generally because you aren't always doing that, you are going in and bairing/dairing/nairing, so they have to react to tons of stuff. Again a fsmash on the ledge suddenly becomes a solid option, they jump wrong and the explosion gets them hit with both, they roll and fsmash gets a charged hit, they wait on the ledge too long they get stage spiked. They jump, you can bair (this only applies if you opt not to charge the fsmash after the sticky) in a timing where they are truly frame trapped, ie bair before the explosion. If they airdodge, they get hit with CB and you can return to juggling, otherwise they get hit. Only a few characters can outmaneuver megaman in the air.
Today ,I hit a CB on an offstage corrin. I tried to trump (trump can work, but sometimes you get stuck...) but she buffered a roll, which happened to be what I chose. We both flew up offstage, and because she had more damage than me
it was childsplay to hit a buffered bair. She was in more stun than me. 4 frames more hitstun and they are combo'd. Any less and you can simply assume they mash airdodge and hit a rising bair or even uair at high damage.
Final note. Full hop fair into landing uair is frame tight, if you buffer it. You get a nice landing uair, and a mediocre spacing fair. This is a good way to learn how to safely uair pressure, sliding away while you land means you are pretty safe.
Also leaf shield is actually alright. When you have a shield up, you still have access to metal blade throws/zdrop/grab/roll/jump. Also, you can act pretty fast out of it. I sometimes just walk up and try and combo a leaf hit into usmash, it can get you surprise kills. You can jump out and try and leafstool, then bair them ASAP for trying to dodge the shield. way too slow for neutral though.
Sorry for typos, this is my low-mid level analysis. Questions, comments, let me have it. I think MM has a niche at the top level for Cloud (still losing though, but not bad at all) Corrin (actually bad for her). Against absorbers, leaf shield + metal blade pressure is all non absorbable =D
MM also does damn well vs Sonic, Villager, Heavies, anyone gimpable... IMO Mario is close to even, you have tons of options. Most MM will disagree and that is fine.