A lot of falco's I've talked to have had problem with this, mainly because the zoning at first glance looks rough for falco. Up air is bad, your other SH options don't reach most of the time, and full hopping is an over commitment and a half. For me when it comes to platform camping-heavy opponents you have to remember the objective. Don't try to overextend and attack them unless you've felt for a strong opening, instead, remember that they have a goal in mind by camping the platform:
Their goal is to change the pace of the game and find an opportunity to gain stage control from you.
They feel that either their options on the ground are losing to yours and it is overwhelming them (laser heavy falco's often force players onto platforms), or they feel that YOU are inexperienced in dealing with them on the platforms. Either one of these is fine, both try to come back to the original goal. But if you never give them any free openings, the net result is you in the center of the stage and they are being pressured. It might feel like they are camping you, but it is more like you are camping them. Even if it feels like your momentum is being shut down, don't do anything that they would be looking for, like trying to shine waveland or immediately full-hop nair/dair them. If you don't do anything silly then you win by have more room to dance outside of their range and never commit, more control over your ariel mobility approaching them than vice versa, and you can do a kind of empty pressure I'll explain in a bit.
Now that you know not to do anything too reckless, lets look at what you can do to fight them:
----------------------------------------------
Abuse lasers: They snuff approaches. The real reason the opponent loses on platforms is because the moment they try to fall through the platform you can move around and they fall with almost no room to drift. Every ariel essentially loses to a laser. This is the number one thing to practice when learning to fight platform campers IMO, because any other kind of pressure you use can force them to use a platform fall-through ariel, and laser beats that with good spacing. Don't be afraid to fire a few below them just in case they want to come back down, just remember to be far enough away sometimes so that they can't hit you in start-up. And of course don't just spam the SH laser in cadence.
Pressure them without committing: This one is like the PPMD special, but you can ironically learn it from the way Smash 4 players gimp against airdodges. The idea is that the opponent gets put in a position where they might get hit, and they are forced to make a decision. Usually a platform camper, especially one that can shield drop, will shield after you dash dance a bit within a threatening range. If you have the potential to FH shine waveland any second, and shielding is all they can do to counter it well, then you can probably trick them into shielding over nothing. After a second or two they can get shield stabbed, and their only great option on the platform is basically nerfed. there's some more to think about, like angling, or them baiting an obvious shield stab attempt, but I can't explain every option they have here.
Approach in ways that counter what you THINK they are looking for: In general don't do the obvious every time. Shines are amazing if you land them, so they will be looking to counter shine more than anything else. I've had a surprising amount of success just wavelanding on the platform and grabbing with a random timing, but that isn't really a great option. Think of weird ways to beat not just platform camping, but what the opponent seems to do on the platform.
Do they SH a lot to bait the waveland/Shine? Then condition them to think you won't FH ariel and knock them offstage with a nair they can't react to.
Do they shield every time you start to run under their space, baiting bad ariel? Waveland grab.
Do they Shield drop early to snuff you when you start to try the first two options? Dash dance like you want to Approach and immediately come back to center stage and laser where they would fall.
If the opponent is camping platforms, then it probably isn't their first time. They usually have a plan that works for them, i.e. they have platform habits.
Use your shield the best ways you can: Last cool thing to try is your shield. If you are below the platform you can bring up shield then immediately act OOS with a roll or wavedash back and bait them into trying and pressuring you. You can waveland and shield by them to see how they react. You can angle your shield to mix up their L-cancel timing from below or even work some shield drops of your own in to throw them off. They are usually prepared to shield drop you, but they usually aren't prepared for you to approach and shield drop on them.
Mix up timings: This one is the most simple on paper but is often the secret bane of some players. Try to make sure that no matter what options you are picking to combat them, you try to do them at timings just a bit off. Even if they hard read your option, if they move too early to snuff you or too late to punish then you can get away with most stuff. In the end this is all about not just getting in a set rhythm of shooting lasers or approaching.
----------------------------------------------
Man that was a mouthful >.<
I like to make posts that organize my own thoughts, so this helps me as much as I hope it helps you. In the end just remember you aren't getting camped, they are. And never forget that every time they sit on plats you have more opportunities to practice mixing up timings and improving. GL and I hope it gave you some good ideas.