Yeah, spring out of chain grab too. If they don't play Sonics often they may not realize that they actually have to buffer the chain grab past 20% or so. Most falcos buffer anyway, unless they are trying to cover a distance, but some forget.
Also, spring if you get daired like syon said, because that way you get up and get some quick invincy frames on the ground making it near impossible to grab/ approach you.
Also, don't CP FD against Falco haha. It sucks and lasers mess up Spin cancelling just as much as spin cancelling messes up Falco's spacing game.
Also, its a ton of guessing when you're in close. You're going to have to live longer than Falco each stock if you want to win, so you have to be able to read him well. Grabbing is crucial in this match-up as you want to up throw him and punish every landing that he does. If the falco is not amazing at lasering then you better be on his *** every time he lands with Up Air, grab, dash attack, spindash or something.
Find out when he likes to phantasm and punish it. If he mixes grounded phantasms into his array often, just hold shield until after he is through you. No use trying to powershield an IAP only to get hit by a regular phantasm. Sonic can punish Falco's phantasm game better than any character if you read well and dont get too predictable on your punishes. Sometimes grab right away, sometimes do a late dash attack and other times do a Side-B cancel to fake him into down dodging and then grab him.
Learn to GIMP. This is really hard if you don't play against real players often as gimping computers is very different. Falco really only has 4 options when he wants to recover and you have an answer for all 4.
1.) Phantasm high to a top Platform (BF,Smashville etc) Up Air or spring up air if necessary.
2.) Phantasm onto the level (maybe try to deke you into thinking hes doing something else) Charge forward Smash if you can time it. Short hop down air works well too. Up Smash is probably the easiest but worst for punishment if you predict wrong and Neutral Air is the best if you're not sure and you just jump around to act dumb and neutral air when you hear the sound haha.
3.) Phantasm to ledge. This is the hardest to punish. Basically your options are to either stand on the ledge and charge a FSmash down like syon said. Or jump above the ledge and drop a spring for a stage spike. OR grab the edge if youre close enough haha.
4.) Fake a Phantasm and recover with FireBird - (Lol go hit him with any aerial. Preferably a backair to stage spike, but you have really just forward air as soon as you leave the edge then old back to the stage and the falco will die haha. Neutral Air and Spring also work. If he does this, then he probably tricked you but if you're close enough he better be dead even at like 40%).
As syon said. Don't get grabbed early. If he gets up a life dont go for downsmashes and forward smashes. Its just going to make you get 70% from grabs. Instead rack the damage up to 180% when you can kill him with lots of options such as ASC or Up throw on a higher platform or something.
Also for a protip: If you grounded spring an IAP at the end of it and then UP air the falco you get 50 cool points!
I actually like Sonic over Falco at low percentage because Falco kinda sucks in the air. I have a combo saved where I get him from 0-50% and then gimp him. But if you still struggle not getting grabbed (like i do haha) then this matchup is really tough as no character is more gay than a Falco in the lead.
-4nace