Falco does great damage per hit and gets legit followups from throws. Combination of a stunning projectile and a reflector is pretty great, too. He's kind of overshadowed by Greninja and ZSS but they have slow grabs (Greninja's dash grab notwithstanding). Falco has a normal one.
The issue is getting in which Greninja and ZSS can just bumrush if they want since pure mobility specs, but they have very rewarding projectiles. Their grabs might be slow, but they have much better range than Falco's and their ground speed can make slow grabs not that slow. Fox and Captain Falcon's Dash grabs aren't fast, but they're fast which makes their grabs seem fast. Falco's slow and his standing grab is among the third slowest melee grabs.
Don't get me wrong, I complain a lot (about Falco), but Falco's strengths are pretty much defining of his character. The only major issue would be neutral. Bad disadvantage is whatever since Fox's is bad and Captain Falcon's just sad. It's neutral where it sort of matters and with Falco's neutral lacking in things like mobility, range, a good projectile, or safe moves like Marth who can throw out disjoints instead of a hitbox-hurtbox or Sheik, it's kind of an issue. Even Zelda's neutral is probably better in a sense that Din's Fire's bad, but you can use it as a distraction, she has disjoints like Nayru's Love, and Farore's Wind can work as a punish and escape options. Oh, someone's going to bumrush you? Farore's Wind out or Nayru's Love them. Oh, and if Ftilt was faster or if it did more shield damage - please, next patch -, Zelda's got a potent spacing tool. Falco has well, a "functioning" Blaster and Reflector which is incredibly punishable on shield. Jab, Ftilt, and Dtilt are all good, but how does Falco get into melee range? I mean, Fox and Falco do share some issues, but imagine if Fox had the same running speed as Falco... Yeah, Fox is probably not going to do so hot, but his Blaster at least has lower end lag and Bair's ridiculous auto-cancel and good range is still there.
The "easiest fix" to Falco would be to boost his ground speed up. His jump is good and having good air speed with lingering moves like Nair and Fair, a strong kill move like Bair, and his Uair would evil. Falco running between Ryu and DK's speeds would make him better as he can advance and chase quicker. His neutral wouldn't suddenly rise up, he'd need Fox's speed at the least, but he'd have an easier time moving towards his opponent. This is a fix where as long as it's reasonable, Falco won't end up polarizing, he would perform better, but he wouldn't magically become high tier. The other would be changing his Blaster. Done in the wrong way, he could end up with something like Sheik's Needles at the worst. That's a move that would take a lot of testing even with "simple" number changes. Reducing end lag would be the other "easy fix". It'd just give Falco an easier time fighting at range. Done right, it could just be Fox's Blaster, but with set knockback instead of Sheik's wacky Needles causing knockback. Of all the things, really? Needles hurt, but they shouldn't slap you back. If anything, it should be the one doing set knockback instead of Falco's.
Falco's advantage someone said was kind of like Captain Falcon's. I don't agree with that, but in a way, it's kind of similar except not as ridiculous. Point being that Falco freestyles which other characters including Captain Falcon do, but Falco doesn't do it in an "easy" way. Falco doesn't have Captain Falcon's speed, but what he does have are fast, hard hits. He combos as he kills and that's one thing I love about Falco. You start off being able to combo a ton and at kill percent, it's the kill move is same move that you comboed with. Almost all characters combo off of throws, but can many characters say the can combo off of any move they throw out? Ryu comes to mind, but at the same time, Fox, Mario, Luigi, Sheik, Captain Falcon, Zelda, Samus, etc. can too, but people just either obsess with throw combos or in some cases, throw combos are much more reliable like Luigi. I bet Luigi could Utilt and start a combo, but it's not as easy as D-throwing. Falco choose to grab or he skips it by using another move in place like Dtilt or Utilt to start. Chillin mentioning that PM Wolf doesn't have true combos, but combos nonetheless through reading DI and knowing how his moves work clicked with Falco in Smash 4. Play perfectly and Falco can take you from 0 to 40% in like four hits, but even without comboing, each hit he does will easily take you to 40%. This is also why stock deficits kind of don't mean much to Falco compared to Sheik where that killing issue does become more noticeable when you have to be on point and that 8 of your hits might only do 40%.
Each characters' play styles are awesome to watch. Ike hits you and you can feel the impact. His combos are usually just 1 to 2 hits, but man, they hurt and they look awesome. Well, to me they do, but people do obsess with long combos which probably turns them away from Ike. Ganondorf can combo if you let him, but being able to boot people and send them off the stage is hilarious, Mega Man plays like he's in Mega Man, and Marth playing precisely and patiently makes him feel like a fencer. At the same time, it does get boring seeing Captain Falcon after Captain Falcon, Sheik after Sheik, and Luigi after Luigi. What's worse is that people cookie cut these characters. Yes, every character has their bread and butter, but if that's all you got and even though it's really good like Diddy's, it's still freaking boring. Seeing Sheik players use Utilt, Dtilt, and Down Smash to start, extend, or punish are great, but it's not really common and if it is, it's because people started copying and attempting to be ZeRo's Sheik or be Boss's Luigi. Even if you have similar play styles, you can be them since you aren't them. I remember a Diddy player who used Banana Peels in a clever way and who didn't use Dtilt when it was all the rage. That was an interesting Diddy. Angel Cortes incorporating Dair to his combos is an interesting Diddy. what's not interesting it Mario player #129389 using Utilt to try and string at 100% because they saw some Mario player use it, but don't understand why it even works.
I'd like to see more Falco, Zelda, Samus, Robin, Toon Link, Link, Bowser, Charizard, Mega Man, etc. play and if that means there has to be nerfs to some characters to even the playing field or better, buffs, then sure, go ahead. I'd be okay with Zelda being top 15 if that means there will be more Zelda gameplay and hopefully sassy gameplay instead of cookie cutter Zelda gameplay. Then again, Greninja is a high tier, but only 1 really good Greninja plays him and is known for it.