Sorry for double post. It slipped my mind.
Updated:
Mario 45:55 Falco, Mario 45:55 Falcon, Mewtwo 40:60 Sheik
woah, woah woah. I wasn't here for the debates about these, but these matchups are not that close.
Mario v Falco: Falco just outclasses mario in every way. Better projectile, has pressure, better anti-pressure, better combos, better edgeguarding, better priority, and better moves in general. The only upside mario has, is that he can CG falco on some stages. Still, it is ridiculously hard to even land a grab on falco. Mario's crappy combos don't help him either. CC also ***** the **** out of mario, because most of his moves are either low-ranged, or slow, or even both. Mario's cape is also too slow to stop falco from spamming lasers.
Mario v Falcon: I used to think it was close, but the lack of range really hurts mario. A good falco will put mario above him, then spam u-air all day, not letting him get down. Falcon's combos are overall better, and it's really easy for falcon to land hits, because of his overwhelming speed. The knee also sending on an amazing angle, can setup free edgeguards on mario at pretty early percents. Mario's recovery sucks, just like falcon's, so there is a way to cover every option with both characters, because of how limited their recoveries are.
Sheik v M2: Sheik's combos, priority, and fast kill potential on M2 wrecks him pretty bad. Due to his terrible weight/fall speed, he gets wrecked bad by sheik's combos.