Mario has some of the coolest dumb ****. I'm just playing around with stuff I'd heard about and he seriously just has infinite crazy tech.
I'm just going to keep posting it here until I get unlazy enough to do a full write up for the vine guide.
So firstly, something no one uses that could be gah-like if you got good at it is cape gliding off ledges at recovering opponents. It lets you place yourself really far out from the ledge while being completely level with it and from there you can use any aerial and have time to DJ and recover. This one is really just good because you're covering a horizontal line from the stage with cape and then doing whatever the **** you want. Bust this out against Ike to Cape his QD, or Nair it if he aims for the ledge. Use this on MK to totally **** his tornado/ Side B shing shing thing/ whatever. It's just mad utility, and really ****ing cool.
Also we've got a DACUS. It's not difficult but I can't really think of a use for it honestly. For styling I guess? Or continuing combos that you wouldn't be able to normally? Actually, think about it this way: if you're comboing and your opponent hard DI's left or right you can use your DACUS as a slightly more mobile Utilt. It's easier on the inputs than (Run > stop > Utilt) and faster.
Wavebouncing is tricky, but can lead to some pretty nifty stuff. WB fireballs are just confusing for your opponent. I gave one of my friends a headache by alternating between WB fireball and regular fireball. Fun stuff. You can also, and this one's kinda hard to follow so tell me if it needs clarifying, WB cape off of ledge > WD back onto stage. This is tricky just for that you can lead an opponent to the ledge, look as if you ran off and then WD behind them, putting them by the ledge and you cornering them. Definitely a gimmick, but not to be forgotten.
As for auto-cancelling, technically, every move in the game is auto-cancellable so the trick is to find the timing. To get you started Uair, Bair, and Dair will autocancel on SH.
Another piece of general tech that can be applied to Mario is crouching and then pressing diagonal back and A will make Mario jab. Seems kinda silly, but the utility is (with practice) you can dash > jab seamlessly, which is pretty sweet. For utility/ things that this is good for you can pressure opponents comfort zone by dashing in > jab > WD back > fireball > etc. It just flows into Mario's ability to move through distances that make your opponent limit their options. Easy mode input for it is push control stick down, roll it backwards (doesn't have to be precise) press A. Easy peasy.
I'll post more random **** later probably. If there are any questions, just post em up.