But here's something. Don't use Falco phantasm all the time, walk forward some with power shields (practice those, they're super important), aggro space, do whatever to gain ground.
When Falco's run speed is barely faster than his walk speed and his ability to force approaches is bad, Falco approaching is kind of sad compared to Captain Falcon, Roy, Lucina, Sonic, and Fox. Ike at least has air speed to go for spaced Bairs and Fairs, but Falco can't do much, but Ganondorf his way while being much more fragile than Ganondorf.
And the thing with disadvantage state, I personally use Falco phantasm in those situations to get off ASAP if they're not too close. Or if they're mad close, I try to Nair, or air dodge fast fall
Falco Phantasm is a slow move, slower than Dair, meaning Falco has to have distance and be lucky that someone failed to follow up. With characters like Rosalina, customs Palutena, Captain Falcon, Samus, Fox, and Greninja having some type of mobility to catch Falco or really good disjoints, Falco can't do a thing. He's going to get beat up like Captain Falcon, Ganondorf, Triple D, Bowser, DK, Ike, and Shulk and he's the least durable one and the one with the quickest aerial to attempt something. Nair's smaller coverage hurts his ability to throw out a hitbox and protect himself like Mario, Luigi, Yoshi, Fox, Sonic, and even Link.
(cuz who falls faster than Falco? Not a soul in this game and if they do, they probably aren't good at aerial juggling).
Captain Falcon, Greninja, Triple D, and Fox all fall faster than Falco. Mega Man and Little Mac have the same fall speed as Falco. Roy's a fast faller too. Source:
http://kuroganehammer.com/Smash4/FallSpeed.
Of those characters who fall faster than Falco, Captain Falcon is an insane juggler, Greninja juggles well, and Fox either will combo you with Fair and Dair, setup an Up Smash with a late Nair, or punish you hard with Bair and Uair.
A combination of slow air speed and fast fall speed means Falco is a perfect, living juggling pin.