I don't know if it's just me, but Falcon is probably the easiest character in the game to gimp with Luigi.
Why?
Not cyclone...
Fast fall dair spike.
Try it. Falcon lines up with Luigi dair spike perfectly, timing and everything. Luigi will spike him everytime. And with the frame data on Luigi's dair, it makes it really potent.
Sure Falcon can use uair to swat Luigi away low, but by that time, Falcon will be too low himself after cooldown to make it back.
(The FF dair spike also applies to Ganondorf. He's a little trickier though to hit)
And Luigi also automatically hits Falcon twice if Falcon tries the full jab with Nair. And Luigi bodies Falcon is disadvantage.
Just saying. If Falcon is on the rise, Luigi will have yet another good higher tier MU. No worse than even for Luigi.
It's probably just me but I have problems with Falcons with Luigi.
Being somewhat close to him is already a super threat because of his immense dash and runspeed cupled with his dashgrab-boost and nice dashattack. This makes it hard to try to approach him and spamming Fireballs doesn't keep him out either.
He combos Luigi fine with dthrow to uairs and gives him a lot of trouble to land again once Luigi is in disadvantage because of Luigis floatiness (takes a lot of time to come back down) and his great uair and other strong punish-options if he reads what you're going to do (things like spaced fsmash or bairs are always really scary, not to mention airdodge-read-punishes with his knee).
CFs jabs somewhat outbox Luigi in CQC, he also seems to get more reward when he hits you with them (or at least it feels that way to me). Everytime Falcon dashes towards Luigi or any character there's some sort of 50/50 if you should shield or not. And every time he guesses right/knocks you up you're in a really bad spot. Oftentimes even 3 uairs can true-combo. I'm baffled every time it happenes because it doesn't look like it would connect, but it does (even when I'm mashing airdodge).
Luigi can combo CF pretty nicely and is also supposed to be able to gimp him well enough, but I'm having so much trouble with this..
First you have somewhat of a 50:50 if he goes high or low. If you guess correctly it doesn't mean you'll get the gimp.
Often when I try to gimp CFs with downB I don't rise high enough at the end to get out of range of their upB. They hit me, take my doublejump that I try to use to get back up, make it back and I die.
It also happens a lot that I try to hit CF and his upB just trades with me. This is of course absolutely terrible if I've already used up my doublejump, which also happened quite a few times for me ~_~. Maybe it's sometimes better to not attack at all and just get hit by the upB, walltechjump and punish, lol.
Now I've thought about doublejump-airdoging up and that might be fast enough to avoid the upB, but I can't possibly be the only Luigi this happenes to... but I'm guessing Elegant and Concon would probably rise high enough at the end of the Cyclone to not be threatened by CFs upB after trying to gimp him with it.
Whenever I'm caught in CFs jab I'm at a terrible position (it's also hard to get back onto the stage from the ledge safely), and I'm not sure if I was ever able to just nair out of them. Well, maybe it did happen, but normally/most of the time it doesn't.
Dair would be safer than trying to Cyclone gimp CF in my case I guess, but it really sounds like it would be hard to hit. First you have to get him offstage too, and then it's still a 50:50 to guess correctly on where he goes. Then he can drift around a lot even during his uair and threatens with uairs so he's not just a sitting duck there that can be hit by anything for free. Even if you manage to hit the dair, getting the spike must be really hard.
It generally feels kinda difficult to land strong hits with Luigi while in the air imo. Bair is super strong, but not easy to sweetspot even if the opponent is in freefall, because of Luigis slowness in the air vertically and horizontally.
Falcon has been a super hard MU for me with Luigi most of the time, but I can see it being even or even Luigis favor when you can mash well enough to get him to fall out of the Cyclone and him not being able to get back from that.
CF doesn't feel as (but still) oppressing in neutral if I don't play Luigi, because of having more range, speed or other safe options.