Well, I thought this was interesting. Using Kirby's customs, specifically Hammer Bash (which is reminiscent of Brawl's Hammer), Kirby can gain a
TREMENDOUS boost in jump height. For those who don't know, Kirby's Hammer Bash boosts any momentum upwards or downwards when used in the air. This was also in Brawl, although I believe it was to a lesser extent than Hammer Bash. I can't remember due to not playing Brawl in quite some time (around a year?).
Anyways, let's get on with it. Not posting the .gifs directly to prevent any lag that could pop up for some users.
Here is Kirby's default jump height, with the aid of Upper Cutter (goes significantly higher than Final Cutter).
http://i.imgur.com/96yZol8.gifv
Now, here is Kirby's jump height with the aid of Hammer Bash and Upper Cutter (although I believe I failed the last Hammer Bash, which carries momentum downwards).
http://i.imgur.com/Grmnmwm.gifv
As you can see, with all of Kirby's jumps, he barely reaches the top platform - add in Upper Cutter, and he makes it to the top boundaries for a split second. Then, look at the increase with Hammer Bash. Just
TWO of Kirby's Hammer Bash jumps (one grounded and one mid-air) equal the same height as all of his jumps regularly. Add in the fact that using Hammer Bash with the rest of his jumps brings him higher than Upper Cutter did.
I wanted to look into this even more, so I tested it against the presumed highest jumper (I'm not sure who it is not with the newcomers), Falco. Here's Falco's default jump height,
http://i.imgur.com/OqNd0EC.gif, and here's two of Kirby's jumps (equaling the regular amount of character jumps) assisted with Hammer Bash,
http://i.imgur.com/gISc629.gif. As seen, Kirby is barely short of the highest jump height in the game.
Now, to test this even FURTHER, I decided to do a little "recovery ranking".
Using the bottom platform seen in this picture (right side of the rock w/ spring), I tested some of the best recoveries in the game to see who could go from that bottom platform to the yellow bridge. If timed correctly, Kirby just barely makes it on top of the bridge. Along with Hammer Bash Kirby, the only other character in the game who was capable of getting from that platform to the bridge is, obviously, Villager. Characters I thought could make it up, such as Pit/Pittoo and Olimar (without Pikmin) surprisingly could NOT make it. As another quick test, I used the same method with Jump Monado Kirby. Instead of using the platform, I fell down to the blast zone (so no grounded jump), and managed to make it all the way to the top and above the blast zone.
Now, of course, this is using Custom Moves. With different customs, almost every character has a custom recovery that goes higher than the default. Now, the real question is
should that character be using that custom in the first place? Going from the "Standard Custom Project", most characters opt to use other custom specials. Whereas, for Kirby, there's absolutely no reason not to use Upper Cutter, and little reason not to use Hammer Bash. Upper Cutter goes higher than Final Cutter, latches on to the ledge, is harder to intercept due to it's speed, can kill off the top similar to Meta Knight's up special at relatively low percents (around 80 to 100% depending on the character), easily stage spikes opponents who try to edgeguard Kirby, can be used to finish off combos/strings in the air, and is a relatively safe OoS option at higher percents.
Hammer Bash, overall, will see more use than the other variants mainly due to the fact that it isn't crap. Hammer Flip can only be used as a bait and punish option, which will most likely not work in competitive play, leaving Kirby wide open for a smash attack. Giant Hammer is a bit more useful, though. Giant Hammer has Super Armor while charging the move, has an incredibly large, disjointed hitbox, comes out relatively fast (fully charged) to intercept grabs, and kills basically every character in the game at 5~10% with full charge. Along with that, it's unblockable, so counters and shields won't work against it. Kirby can instantly kill Marth and Lucina from a shield break when they're only at 8% (Jumping Inhale) from the middle of Battlefield, which gives it a bit more use.
As apparent, the boosted Hammer Flip jumps barely give Kirby any horizontal momentum, and more so focus on vertically boosting his recovery. The solution to this is simple. Jumping Inhale, which is similar to Upper Cutter in having no reason to not replace default Inhale, carries Kirby from every vertical blast zone right next to the ledge, to safely Upper Cutter back onto the ledge, or quickly jump towards it with any remaining jumps.
Using all these recovery options, Kirby seemingly has a bunch of mix-ups for recovering. Kirby can essentially double the height of any jump with Hammer Bash, recover from any blast zone with Jumping Inhale, can easily fly from the bottom of the stage to a ledge with Upper Cutter (and stage spike anybody willing to challenge Kirby), along with multiple jumps to go along with it. He can also drop down quickly to recover low using Stone, giving opponents less time to set up for edgeguarding. The only thing stopping Kirby from having one of the best recoveries in the game is his vulnerability and atrocious air speed. However, having so much options for recovering, along with his already good recovery, means that gimping or edgeguarding Kirby will be significantly harder than others. From personal experience, the only time I have ever failed to recover with Kirby is from @
Spirst's cans from Duck Hunt, along with being stage spiked (although this is rare when using Upper Cutter).
Please excuse my lack of, er, sentence structure. It's quite a mess, but hopefully people will understand what this post is about. Also, this was typed up fairly late, so please bring up anything that doesn't sound right in general!