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Falcon vs Mario is = or advantage Mario, but now we can actually discuss the matchup.
First of, Fireballs aren't too valid a reason. Even with smart use, Falcon can cancel them out and go less out of his way doing it than many other characters. It does affect him, but Mario leaves himself vulnerable by throwing a fireball. They still help Mario, but don't @#$% Falcon over. Just a minor advantage Mario has on-stage, but a major one when it comes to recovering.
Both Mario and Falcon tear the other part. Mario can't combo Falcon as well as Falcon could combo himself, but again, same goes for Falcon comboing Mario [as in, can't combo Mario as brutal as he could some other chars]. He actually can combo Mario, to try to prevent that point coming across. Falcon can start a combo with usmash, grab, pretty much any classical way, and get the set of uairs->upB, but he can't uair as long as he can some other characters. On the flipside, like smoke says, one drill->uair and Falcon's dead. Sadly, you can DI behind the drill even with average DI at least some of the time, but Mario is capable of turning around and grabbing Falcon if Falcon DIs behind the drill [which leads to the next section].
Off stage, Mario wins in all respects. Mario makes it back easier [the likelyhood definition, not skill one XD] to the stage than Falcon, and once Falcon is off he's dead [a good Mario should ALWAYS edgeguard Falcon except in a select few circumstances]. Falcon can edgeguard Mario, but it's not guaranteed due mostly to it's incredible distance, UpB's priority [which clashes with dair, unfavorably for Mario] and fireballs [fireballs count when Mario is recovering, cancelling them out helps Mario make it back]. Setting up though, Falcon has his uairs->UpB combo, and Mario is stuck relying on grabs and fairs/bairs, and the only way he can really get grabs is by comboing into them [with drills, for example, but that helps set up for an off the top kill]. A failed dair->uair can help Mario edgeguard though, and Dsmash after a dair/fair is also viable.
On Dreamland, it's = to advantage Mario [methinks advantage Mario]. Mario combo ***** Falcon on that course, finishing up uairs with a usmash through the platforms, and fireballs become harder to dodge [I think...I notice Link's bair cancels fireballs better on DL but I dunno Falcon]. On Hyrule...I think it's = to advantage Falcon. Mario can't take advantage on his off the stage trump card as well on Hyrule, and his combos are weaker there [except for the **** tent].
I have to do homework, I'll type out Falcon vs Ness later. That one is = to + for Falcon, but I personally feel it's =.