Yo what's up! I'll drop my thoughts since I **** on falco. I do pretty well in my region for it, have some decent wins.
Lasers approach in a very horizontal plane, obviously. Create pressure off of the main plane. Unless your power shield game is on point, don't be afraid to use the platforms.
But don't just jump on a platform and wait. Do things. Make sure when you do things on platforms, you create scenarios where you can punish falco coming from beneath you. Ultimately, your goal is to force falco into a scenario where he can't cover the horizontal plane, and instead he is forced to come at your from vertical. Here's the tricky party, Falco is powerful vertically too.
But suddenly you can compete a lot easier when you force Falco to approach. It's hard to conceive this notion considering the difference in projectiles. But if you can escape to a platform and charge a few needles, you will force falco to approach you. If Falco doesn't take the bait, now you have needles to play with for platform drop needle grabs etc.
I would keep working hard hard on just doing things on platforms such as shield drops, and just honestly learning how to move yourself comfortably between them, it's essential if you struggle with lasers.
However, I think the most powerful counter to lasers is Power Shielding. It's a tough timing, but worth practicing. Falco has infinite bullets, but suddenly, if even one out of every 5-6 lasers gets sent back, the Falco might put a few less bullets in the clip.
If everytime Falco lasers, his chances of getting that same laser (with hit stun) back in the face is greater than 10%. Suddenly it's way more risky every time that Falco short hop lasers.
What this pressure of potential Power Shielding does, is alleviate laser pressure obviously, but it also gives you an opportunity to play on even ground with Falco, which can neutralize his vertical pressure.
So I would look to two ways to deal with Lasers. Play the platforms and disjoint the horizontal plane falco is trying to establish, and just don't be afraid to try to power shield. I know I can power shield, and when I play tournament matches. I count on myself landing one out of three. Could you imagine how scary an opponent is for a falco player, if they can't laser? Just some thoughts on those.
So I'm still working on my spacie edge guarding a whole year later. It's honestly slept on pretty hard. You have to get in the habit of acting on your opponents positioning, pay attention to where your opponent is headed, and what they way. Needles covers the horizontal space above the ledge. No need to be so quick to jump out after a hit. Watch, React.
If I can smack them off stage from somewhere not super close to the ledge, I will try to cover the horizontal with a needle, THEN react. This let's you cover the immediate side b over the ledge. From this point you move towards the ledge and react to where they position their character. If the spacie lets themselves drop below the edge, from this position they can ONLY UP B. So in this position, take ledge, either back air, nair over stage etc.
Drop down and fair up B's is really dank, but chill on that and trust in your characters Bair. If the spacies chooses to Up B and they are above the horizontal axis of the ledge, you can jump out and fair them, you can turn around bair, you can Reverse needle cancel into a bair !
I would chill on the dj nair. Honestly, it's a great option, but beatable because it costs you to commit. Spacies will call you out on it if you try to force it too much.
Final edge guard thoughts: You can do it, just relax, your character isn't this bionic machine. Take your time and flow with optimal reactions.
You will ALWAYS regret letting a spacie live after you get them off the stage.
Okay, Im way too out of it, I don't even know if this advice was good, hope some of it helped at least force you to think about some different ways to approach Falco. :D