i'm not a smash pro or anything but i have a very solid fox against falcon and can usually take out falcons of a generally higher skill level. here is my take on the MU.
in the neutral game, stay on the ground and keep your distance. you have a laser, so use it. make falcon approach you. he is going to be coming at you with nairs all day. luckily, a smart fox absolutely murders this approach. you want to have a tight dash dance game. no matter how fast the falcon is, and as long as you dont get trapped with your back near the edge, fox can dash back and punish falcon in his landing lag. its best to always stay in the dash dance in this situation, so i will punish with either grab or running upsmash. if the falcon does corner you near the edge, however, uptilt is your best friend. a well timed backwards facing uptilt will almost always (in my experience) beat out falcons nair, and uptilt is easily fox's best combo starter in this matchup. alternatively, fox can always dash under falcons short hop nairs, but i usually only do this when im in danger of being cornered. from here you can eat his lunch with a bair, or just reset your position, but now falcon is cornered by the edge, and thats an even worse position for him than it is for you.
from an offensive stand point, i understand that it can be hard to get in on falcon, but your best bet is to get him to put his shield up. once you hit falcons shield, that is basically like landing a hit. he cant do anything out of shield. i have a generally weak shield pressure game, but you dont really need much of one against falcon. drill the back of his shield. from here, mix up with either an uptilt or just do nothing. most falcons will roll away at first, so i usually just drill, wait, then punish the roll. but if they start to catch on, they will probably try to nair or stomp out of shield. this is where that uptilt starts to pay serious dividends, as a properly timed uptilt here will catch them jumping out of the shield, but before their aerial comes out. also, a lot of falcons do a quick double jump here, so the uptilt literally *****. falcon in the air with no double jump against fox should be the stock if you are patient and on point with your punishment game. there are probably better things you can do if you get his shield up, but this is just something thats safe that works a majority of the time, as well as frustrates the hell out of them. i would like to hear what others do to falcons shield.
edgeguarding falcon is simple, but easy to screw up. the biggest mistake i see most foxes making is not maintaining control of the edge. falcon has a lot of recovery mixups/mindgames that allow him to get to the edge. the best way to prevent this is to just stay on the edge. just reset invincibility and try to shine the piss out of him, no matter what angle he tries to come in at. just make sure you dont miss and drop the edgeguard. if he lands on the stage, either do a bair from the ledge to continue the edgeguard (you have to be very fast or he will shield) or drill shine to upsmash if he is at kill percent. if your bair sends him at an angle where he is forced to recover high, go ahead and get on the stage and charge forward smash. if you space it correctly, it will connect whether falcon tries to drop in and grab the edge or land on the stage. just make sure you dont do it in a situation where falcon can make his up B land behind you and it is a guaranteed continuation of your edgeguard. watch colbol against falcons to see how to forward smash like this. this is preferable to the bair imo since charged fsmash is considerably more knockback and damage, especially since for any normal fox your fsmash is going to be less stale than your bair. also, as a side note, i would generally avoid trying to shine falcon below the stage unless he is in lag, or unless you are invincible from the ledge. just be patient. you dont want to piss away your stock because you got greedy with a shine and caught an up B in the mouth. that's a two stock swing.
regarding combos, i usually use a more intuitive approach than any percent specific stuff. he seriously just drops like a rock. dont ever be afraid to let him hit the ground in a combo because tech chasing falcon with fox is so simple that i almost prefer it to the simple nair/uptilt/upsmash aerial combos. his get up attack is a joke to punish. falcon's only real hope of escaping fox once he gets hit (at really percent really) is the double jump. respect that. dont just jump at him with a random aerial after he double jumps out of a combo, because if he is good you will often get hit for it. just laser and reset your neutral game because fox is always at an advantage there.
watch cactuar if you want to get a better sense of how to get that first hit against falcon. he wrote the book on it.
watch colbol for how to get guaranteed kills when you have falcon in a combo near the edge.
every time i see fox lose to falcon i die a little bit on the inside. falcon should seriously lose this matchup before the game even starts.
