[Me vs S2J] (Use this video as references for the times below)
http://www.youtube.com/watch?v=Tok74dKjeR0
Dealing w/ Falcon's nairs:
*you can space them if he tries to overshoot w/ a wavedash or good dash dance game
*if he does retreating nairs, fireball that sh**! or wavedash up to him/running fsmash(don't take the bait, take the space)
Example of dodging nairs: 05:55-06:00
Uptilt Pros:
The thing about uptilt. You have to use it like a Fox shine. Use uptilt to cover the gaps in your offense/defense. It's a VERY good move to shut down falcon looking to punish Mario's laggy moves.
Examples that shows a whiffed move getting covered by the uptilt: 01:29, 04:12, and 5:50
& Cons:
Now if they catch on to you uptilting a lot, they can actually knee you out of shield(I THINK???)/grab you(if you're close enough) if they block it.
Example of getting grabbed out of an uptilt: 11:10
Shutting down Falcon's air game:
To keep him out of the air is another strategy. I use dair A LOT when I'm in center stage since there's 80% of the stages w/ platforms, the center is the only place that would feel completely free for Falcon to full hop and do something. So if you dair center stage(full hop dair is what I mean), then it'll stuff almost all his moves. And just do that as a warning for him not to approach you recklessly.
Examples of shutting dairing his aerials: 07:03
Falcon grabs you:
If Falcon grabs(you should be holding "away" 95% of the time due to Falcon follow ups. For example, if you DI in while he dthrows you, in mid-high %'s, it's a legit combo. But if you DI away while he dthrows you, you can up-b challenge/up-air/jump out of every combo. That's the advantage Mario has on Falcon.
Example of getting dthrowed my DI "away" 11:42
I feel like I've stated these things before, and if I have, sorry. Ask me anything else if you need more help killing/edge-guarding him or other characters