I'm interested in what you think.
k...
intro info stuff:
IMO this Match-up could be anywhere between 55-45 Mario to 60-40 Pit...so I have it at even-ish for now.
Major deciding factor in this Match-up so far is Stage selection. Anything with a wall and Mario is suddenly on your level of recovery(higher in some cases considering he can survive longer on YS/WW for example).
The best stages to pick in my experience so far(depending on rules of course) Battlefield, Halberd, Kongo Jungle, Skyworld, and Smashville because there is no wall to up-b tech for Mario. Following those would be Pokemon Stadium 1, DL64, and Rumble Falls. Although they have walled sides they aren't as long or as easy to wall jump with up-B and they also have plenty of room for you to play like a ***. Stages to avoid would be Dracula's Castle, Yoshi's Story, Yoshi's island, Warioware, Green Hill Zone, and Fountain of Dreams. The Stages I didn't mention seem good for both characters. Those stages being Final Destination, Norfair, Skyloft, Metal Cavern, Castle Siege, Pokemon Stadium 2, and Delfino Plaza. In conclusion...the stages lists will decide the fate of this MU in the end but for now I'm sticking with evenish....
Mario vs Pit
As soon as the Brawl announcers says go! the first thing Mario and Pit will do is press Neutral B so I'll get this out of the way. First things first is the camping war, in my experience you lose on anything mid-small size stages and you win on large-giant sized stages. Pit likes it big, no shock there. The reason why actually comes down to Mario having the superior reflecting tool. Pit's Mirror is good, damn good but not nearly as good as Mario's cape. B-sticking with Neutral-B and using Mario's cape it allows him to get into offensive and passive position fairly easily. You can leave your shield out for days but on mid-smaller stages Mario has enough time to get to you and punish your end lag or even worse. He can humiliate you by using the cape on your mirror like it doesn't exist damaging you and turning you around so he can give you a prostate exam. Of course on a larger stage you have enough time to play this projectile/reflecting game while remaining relatively safe from punishment. This will be a very very gay match if pit and mario both are committed to dominating the projectile game and not offensively minded.
The only chances you have in this area on a small stage is to get above doc and try to rain arrows down on him in the hopes that he will start high jumping since his fireball will only go as high as he jumps. from there you can fly in under him knock him higher up in the air and keep him there or, if you are feeling froggy you can bull rush Mario and try to keep on top of him so he doesn't have room to spam. Both Mario and Pit have a Clank-able projectile. Meaning you can Nair through Mario's Fireballs like they are candy and Mario can do the same thing to your arrows but I wouldn't recommend it as an initial approach for either. The main reason being there is a good chance the fireball or arrow could angle the hitbox in which case you get hit and put into bad a position. However with more experience and in the MU I would suggest Nair walling through Mario's Neut-B because the reward(another Nair and/or double fair which can lead to potential death if you edgeguard well) is great enough.
All projectiles aside The Match-up can be easy with Pit if you remember the 3 most important things in this Match.
1.Spacing
2.Spacing
3.SPACING!
Pit's aerials are fast and most of the time if Mario goes for one at the same time you do then you will beat him out(especially the Fair). I've also found a home for Reverse Bair combos especially on the extended combos that might not make it in time before the cape. Should the cape turn you around you will get your standard Bair attack on mario which means you may have a chance to then continue combo'ing or edgeguarding Mario depending on which hitbox he gets hit with. Pit's Jabs have an interesting function to remember, 2nd hit pulls opponents in, 3rd hit knocks them slightly out, Pit's tilts can also auto-cancel after the 2nd jab, Meaning you can A-A-Ftilt, Utilt, or Downtilt for some interesting mix ups and Combo starters/kill setups.
Some aerials if done right can be shielded without you getting destroyed but be careful. Mario is capable of punishing bad habits and just plain dumb approaches especially Out of shield. Mario's combos rival the best of them now and he can combo you into aerial or grounded finish(fair or Fsmash). So if you are hit/grabbed by a good Mario it's important that you know the Combo DI and the correct throw DI to avoid a painful finish to your stock or massive %. Often you'll be in a position where you'll have to pick the lesser of 2 evil outcomes though. For example DI'ing the Dthrow away from Mario might put you on a platform or in position to be tech-chased at low%, but that is nothing compared to DI'ing wrong and getting 40%-death. So...my personal advise for overcoming this MU is safety first. save the Flashy combos for fast-fallers and bulky characters.
Getting Mario above you is your ideal position(no homo). Uair, Usmash, arrows and well timed Up-B are pretty much doom for a Mario who lingers above you. As long as you can keep a good read on him you should be able to follow him with Uairs and switch to a Nair or Fair at higher %'s to lead him off stage.
This is what I got so far. Anything to add?