There was a problem fetching the tweet
How to DI versus Falcon aside, his side B has 10% worth of damage based armor, but can either lift him off the ground with d-tilt before it comes out, or everything except the furthest late hitbox of Mewtwo f-tilt, the sweetspot of dash attack, fair, and bair should be enough to beat it out. Uair too if Falcon does side B from the air.
Raptor Boost will armor through the rest of your normals though for the most part. Otherwise just shield the move. Far as what to do after shielding it, either an OoS option (but be forward and quick with it since Falcon side B bounces off of shield but has enough end lag), anti-air like up angle f-tilt if they do the aerial version, or step/fullhop back and see if they panic spot dodge or roll back, then see what you can do. If you're at somewhere high % when hit by it and launched higher, can also nair as a get-off-me before he manages to do an aerial followup, I believe.
Be careful not to swing too much against Falcons that know your character since his movement can be tricky. You need to find a sweetspot of waiting and putting out hitboxes to control space. He usually needs resets or certain platform positioning to get his busted combos out, so keep that in mind so you're not too linear in disadvantage.
Falcon’s u-tilt and u-smash have intangibility on the legs, so don’t challenge directly if recovering from above. Also be aware that his d-tilt has a 50% chance or so of causing tripping.
Oh, with shielding Falcon Kick, just be aware of its ability to crossup your shield and do a turnaround attack as a punish during its end lag. Also keep the aerial version of the move in mind if they stall above you or do a ledge jump.