Often when I'm edgegaurding Falco and he's above stage I'll move back a tad bit to punish a side-B onto stage/platforms. However recently when I do this, the Falco/Fox just shortens it and drops to ledge. Any tips on how to cover this?
Ok first off remember that Fox and Falco's recovery's are different. (despite them seeming identical) Fox's side be is a little slower and Falco's up B is way shorter and wont burn you on start up. Falco can't move vertically through the air like fox can. That's a big think when you're edge guarding and they have a double jump. Just keep that in mind.
Anyway so covering side-b is super important because it is the spacie's BEST recovery option. These are a few tips to keep in mind when covering side-B.
First stop backing up preemptively.
Walk right up to the edge and cover the side-b on stage, edge grab and shorten all at the same time with double jab.
All that's left is for them to recover
high with side-b. (Side-b high to get on stage is trash because they have to fall down into your loving arms.) Now you have to cover platforms if they do a high recover. They side-b on the top platform but that's a far way to go and you can read it like a book. punish with a up air -> f-smash or something. They can side-b to the platform your under but... your under it. They can platform cancel there side-b on the platform your under which is a pain to deal with when your not ready for it, but by the time they get it off you should be where there gonna land and punish. They can shorten High to try to trick you. That's super risky cuz if they don't your right under them ready to F-SMASH! or dunk for style.
Be patient and
react. not predict.