Float higher than he can shoot, then space with fair
If you can't hit it, don't sweat it or freak out and do a panic dsmash. Usually you can just regain your elevated position, and be happy that he had to give up some stage. It's really hard for Falco to get meaningful punishes on missed fairs, because he's sloooow. At some point he will have to cross you because there isn't any more stage to retreat to.
Just try to avoid whiffs that leave him super close, if those happen you might want to shield / jab (or mix in the dsmash occasionally). Or dash away (too few people do that in general imho. Peach dash away after fc aerials is sooo good :D). Just be sure not to dsmash everytime, because that way you are opening yourself up for easy punishment.
(I don't think there's really need for a "what do I do if I hit him or his shield?" part but just in case: if you hit, you get a techchase. Tech roll away is pretty safe for him, and there's times where you can't punish it at all. But he has to give up space, so that's pretty much what you want in the first place :D If you hit his shield, you can go for the usual peach shield pressure mix up stuff (jab, grab, downsmash, dash away))
Once your close enough, you can try to dash attack him for shooting unsafe lasers.
Shield > jump oos > float at your desired height can be really useful if he tries to lock you down with lasers
Regarding what to look for (those are pretty much my own opinion, so you (or others) might disagree entirely).
below 20ish percents: fair > techchase > Grab > upthrow > downsmash. Or parts of that (not every grab comes from techchases, mixing in dthrow techchases can be useful, etcpp).
between that and ~70ish: dash attack / dtilt / grabs into combos or the chaingrab. If possible at least end with a edgeguard situation if you can't secure the kill right away.
after that: basically any aerial that will put him offstage.
Of course there's other neat things to get, e.g. you can chaingrab him well after 70% (I just think it's way easier to hit aerials than grabs... if he shields the aerial you could catch a grab though, so that'd work out pretty well if you want to CG anyways... :D), those are just what I generally would like to get. Of course there's situations where you just
know that he's unprepared for something different... if so go for that obviously (:
Regarding defense:
If you can't get up a fair wall in time, you can still try to trade with him using groundfloated bairs (or nair or dash attack if you can get the spacing). Or just shield and work from there. Few Falcos like to grab, so shielding is pretty decent, especially if they go for the same type of shield pressure every time. Try really hard to not get predictable what you do oos, because most OOS options are easily punished if Falco expects them
If he likes to dair you at low percents, you can try to float into him in order to land with no lag after the dair (I think this works to about 20 percent, and if he catches on and goes for nairs ... your goto CC > stuff works well on those :D).
Dash dance > stuff can be nice as well, especially if he tends to want to approach instead of sending in lasers.
edgeguards:
Turnips are super good for covering one or more options (I especially like it vs the sweetspotted illusion height).
If he can't hit the sweetspot from his position or you think he'll miss it anyways (or is afraid of edgehogs), you can use bair / nair (/ fair, but I think that one is usually too much risk (timing difficulties) for what benefits it offers. But if you can use it and hit below the stage as well, more power to you
) to send him back off again.
Dair is really good against sweetspot firebird from below, especially if you can get a spacing that will keep you safe from its hitbox. (dair > turnip pull > dair his second up b > throw him dead is fun :D).
If he uses up b above stage height it can be really tough to edgeguard him, so don't get frustrated if you miss it. Also, you might want to try and catch him offstage to avoid having to guess whether he goes high or for the edge (weak aerial > strong aerial is great for these).
If you float near the ledge with your back turned against it, you threaten to do both bair / a simple edge hog, that can be really helpful.
sorry for this mostly being a huge mess of random tidbits of information, I'm just not a very organized person I guess :x :D
and I guess I got kinda carried away, since you basically just asked how to get around lasers to which the very simple answer is: "float above them" most of the time (:
