YES actually ha ha **** sorry guys I got carried away and was looking way too far ahead. No yeah for now lets discuss the characters in the demo instead.
Is this more geared toward talking about a specific MU at a time or an open talk about whatever MUs we decide? You had Little Mac listed as a good start, but I wasn't sure if we could discuss other MUs if we didn't have much to say on Little Mac or wait until we moved on from LM. Otherwise I was going to suggest starting with one or two of the demo characters since that's what the majority of us have played against.
I would suggest that for a while we do open discussion, then after maybe a month or so after release (or whenever the meta begins to legitimately develop) we move on to structured weekly or biweekly character discussion.
Anyway that being said I'll give some input on the Mega Man MU now.
Okay so in my opinion Mega Man is kind of a bad character, mechanically speaking. He really lacks reliable KO options that aren't telegraphed, and his quicker attacks are on the weak side. For the most part, Villager can really outspace Mega Man because his NAir and FTilt are relatively weak and have lackluster range, while Leaf Shield and Metal Blade are slow and can easily be shielded or Pocketed.
Pocket really shines in the MU because of how much of Mega Man's moveset it covers. While you're usually better off not wasting inventory space on Metal Blade, Pocketing Crash Bombs and throwing them back is really nifty. If they stick, the Mega Man is forced to either approach you in an attempt to pass the bomb to you, or shield/dodge the explosion, creating an easy opportunity for you to approach. Leaf Shield is really slow when launched, so Pocketing it is easy as well, and SHing it is the best way to go because then it effectively neuters most of Mega Man's approaching options and significantly helps your own Tree camping.
FSmash is really readable, but most of the time I think you won't have an opportunity to Pocket it because you'll have something else in your inventory, so it would be better to spotdodge and use the crazy cooldown to your advantage. At close range I think PS > grab is guaranteed, but if you don't want to risk the net's wonky hitbox screwing you over, SHFair, FTilt, and DTilt are also good options.
You can also Pocket Rush. It isn't of any significance, but stuffing a dog into your pocket is pretty hilarious.
Tree is sort of eh in this MU. On one hand, it blocks a lot of Mega Man's approaching options and makes it risky for him to approach at all. On the other hand, if you're standing too close to your tree when a Crash Bomb impacts it, the explosion will still get you, and if you're in landing lag from firing off a Lloid, you might not have enough time to shield it. In general you need to be aware of the explosion's hitbox so you don't get any unpleasant surprises. Metal Blade also completely ignore the tree, passing right through it, but unless you're in some sort of lag, its still pretty easy to deal with. I don't remember if Leaf Shield can pass through the Tree, but I wanna say it does. If Mega Man somehow does manage to get right up against the opposite side of the trunk, it usually isn't too much of an issue, because depending on the distance Ftilt and Jab will be blocked, and if they're not, the damage is pretty negligible. DSmash's hitbox will always reach across the Tree in this situation, but it has noticeable startup. What you really should be worried about is SHFair, because it comes out pretty darn quickly, reaches across the Tree, and is quite strong. SHBair is the same case, but I don't know how easy it would be for them to turnaround hop or RAR, or if RAR is still even in this game. Overall the Tree still has utility in this MU, but given that Mega Man has options to hit you through it, it isn't as great for camping as it is against other characters.
In general if you want to approach you can do SHFair to block incoming blades and bombs, though since this will also neuter your attack, SHNair might be better since the hitbox remains active and you don't suffer bad landing lag if you don't FF it and if you don't do a double SHNair. SHFFFair is the way to go to actually hit Mega Man, since most of the time just SHing it will either make the projectile go over Mega Man's head, or if it does hit him, it'll be because of the end arc, and the damage and knockback are both lame at that point.
Mega Man's recovery also makes him really easy to gimp, but if they're not recovering low you have to watch out for Crash Bomb stage shenanigans.
However, you're gonna have trouble if you're above Mega Man. Villager has a nasty blindspot below, so getting juggled is really easy. Despite how powerful it is, Utilt is easily read, so you don't have to worry about that. USmash on the other hand comes out quick, racks up damage, and has a strong finishing hit. I think Uthrow > SHUair is also viable, so you REALLY need to be careful not to get stuck in the tornado. I wouldn't advise trying to Pocket it if you get caught, because the rest of the hits will probably cause Pocket to fail and you'll suffer damage anyway, so SDIing down and to the side is probably your best option.
Mega Man will be able to edgeguard you sort of decently. After your first ledge grab, DSmash really allows him to cover you, forcing you to either drop down or hop away. If you hop away you can nail him with Fair, and if you drop down, you can time a wall jump so that you rise after the hitbox is gone, and you can hit with with a strong Bair. USmash can still cover you if you try jumping over, and in this situation so will Utilt, which like I said is a really dangerous KO option for him.
You also need to not be reckless with your approach, because even though there's not much Mega Man can do to shut you down, getting grabbed while he has a Leaf Shield up will rack up a nasty amount of damage.
As far as stages go, at this point I guess you should avoid platform-heavy stages because of how easy it is for Mega Man so juggle you, and because you already have a significant advantage anyway. Flat stages really shut down a lot of his options and makes it harder for him to get Uairs to connect, while forcing his approaching behaviour into a hard linear pattern.
At this point though I don't want to be confident in this analysis, because the only Mega Man main I've played is of questionable technical knowledge, so I want to wait until we see more tournament material so we can really analyse the character's playstyle. For now though, I'm gonna say this MU is around 65/35 in our favour, solely because Mega Man isn't completely defenseless and definitely has situations where he will be in control, though he lacks ways to follow up on these leads