Advantage State
Advantage is what occurs once you've hit your opponent and attained stage control. This is where everything truly counts: pile on the damage, put 'em away. Your sole aim here is to kill them. Take their stock, put 'em away, by whatever means necessary. If they somehow get out, it's not without taking ludicrous damage. K. Rool has among the highest damage output in the game, dealing like 20% per hit sometimes. Playing to this is essential to win consistently.
Movement & Pressure
This is less of a guide and more a mythbusting section. Players often start mashing the second they get into advantage, and I'm here to say that this is the worst thing you can do when you get advantage. You can't just hit your opponent willy-nilly: you need to get your combos, mix them up, and most of all, keep them in a situation where they remain in disadvantage. The angles in which you've sent your opponent, as well as the lag on your attacks, will determine this. Keep an eye on where your opponent is, what they're doing, and exploit these to the best of your ability.
So if you're not in a situation to strike the opponent in disadvantage, liberate yourself a bit. Instead of mashing FAir and getting punished, go for movement. Get yourself into a better position to attack instead. Once a player has been hit, their mind immediately shifts into "disadvantage" mode, they're going to want to try and get out. The best way to do this is to, obviously, pick a defensive option. By not committing to lag, you are in a position where you can shield or otherwise defend against these options and reset their situation, forcing them to rethink. This applies a ton of pressure and will make your advantage state much more effective overall. If you want a simple way to apply this, try using UThrow and waiting there. Oftentimes, the opponent will mash a landing option. Since you're not trying to follow up with the obviously untrue UAir, you are now in a position to punish it. Try moving back a bit and pivot grabbing, or even just using a delayed USmash. Try looking at the Hit Advantage document and seeing where else you can apply situations like these: as a general rule, if there's no followup, you still have mixups.
Combo Game
King K. Rool's combo game is limited, but significant. All the combos he has deal exceedingly high damage and often leave him in excellent situations. It's up to you to make use of these situations to extend your advantage further, as mentioned before.
On a side note, never skip out on pummels whenever I mention getting grabs. Your pummel literally deals 2% fresh, is among the fastest of the superheavies, and is even fast enough to be virtually guaranteed at 0% if you buffer the throw. It's disgustingly good and unstales your moves too.
Here is a basic combo guide. This doesn't go over bury jank, but it's enough to get you started.
FThrow -> Dash Attack: Your 0% Opening
FThrow -> Dash Attack is a true combo without any opportunity for interaction from the opponent. For a good source, click here. FThrow is unique in that it doesn't send opponents into tumble while providing massive hit advantage. Because it's a throw, it cannot be SDI'd. Because it's not sending into tumble, it cannot be DI'd either. As a result, you can literally practice this confirm in training mode and get the same interaction in a real match. Do not skip out on learning about this, as the 30% you get is valuable for DAir confirms later.
FAir + FThrow Combos
K. Rool's main combo enabler is his landing FAir at lower percentages. This is because it can be as much as +15 on hit at 0%, while inflicting non-tumble hitstun. This makes it a free grab, or even a DTilt with perfect landing, though this is more specific. Because of this hit advantage, you can use FAir -> FThrow -> Dash Attack for around 50% right out of the gate against most characters. Alternatively, for a near-instant ledgetrap situation, Dash -> Jab is a valid followup. It's very, very common to see K. Rool fish for FAir at 0% because of this, as it's even safe on shield.
Once around 25% has passed, FAir becomes a tech situation enabler, which you can use to get Jab or DAir Locks. If you want to cover every tech option, Crownerang is a valid option, but this often comes at the cost of a lot of potential damage. Dash Attack is also valid as a true combo for around 38%. Yes, you read that right, 38%. And that's not even as much damage as you can deal out of a tech situation!
FAir's combo utility after around 50% is fairly limited outside of specific situations on the edge of the stage, which aren't something that would really fit in this guide. However, it remains effective for maintaining advantage due to its brutal knockback angles.
It should be noted that NAir's early hit is virtually identical to FAir in what you get out of it, only it sends into tumble a bit later and has a worse hitbox.
Late NAir Combos
NAir's late hit is very valuable, not sending into tumble until around 65%. This makes it a free grab almost all the time, or Dash Attack for a true confirm that basically says "your advantage is mine now". However, it doesn't start being good for combos until 25%, so make sure to open with FThrow -> Dash Attack as soon as possible so you never have to worry about it. Remember that the early hit does confirm it at 0% though, it is literally a FAir clone in regards to hit advantage.
DAir Combos
DAir is a bit more difficult to land in comparison to K. Rool's other moves, as it's mostly vertical hitbox-wise. However, if it connects, it can enable formidable combos at 40-50% with DTilt, and grounded spikes thereafter further provide options, including near-guaranteed tech situations at 50-60%. It's recommended to use DAir out of DTilt for these reasons.
Juggling
While K. Rool is designed to attack horizontally a lot of the time, he has a limited but effective juggle game that can be devastating when used to good effect.
It's no secret that K. Rool's UAir has enormous endlag, but this isn't a dealbreaker like many mid-level players like to talk about like they know everything. K. Rool falls like a brick, so the lag ends up not mattering too much. In fact, it's much like any committal "Full Hop Fast Fall" aerial in that you can only use it once in a jump. Not only that, when it hits, there's so much hitstun that you're often still in advantage once you've cancelled it on a platform. When you think of it from this perspective, it makes a lot more sense, right? The lag is there to offset its sheer power and protection, both of which make it one of the hardest-to-challenge moves in the entire game. I'd personally argue that the risk-reward is skewed in K. Rool's favour, since the move can KO characters at like 80% during a juggle situation, and you can absolutely chain these together when utilizing platforms to cut the lag off. If you hit them, they die, if you miss, the opponent is probably still trying to land by the time you're down. Remember that you will almost never see the full lag of UAir unless you're recovering, so it really isn't that big of a deal in practice.
An oft-forgotten part of K. Rool's juggle game is his UTilt, though. It reaches so ridiculously far up that it can be seen as an aerial attack to some degree; it even has some intangibility to assist with this, albeit with a large hurtbox extension that can be a nasty punish if it fails. It often gives just enough hit advantage to provide a mixup situation: catch their landing aerial or airdodge with a grab or second UTilt, or chase their jump with UAir. When sharking platforms, this often gives a near-riskless UAir, as you can SH UAir to the platform and only experience the landing lag, often giving the perfect frame advantage for another mixup. Don't try to directly follow up from UTilt though, as nothing out of it really works. What you do get is the perfect time to sit down and farm information.
Keeping them in the corner
Before moving forward, the above video is a required watch to better understand the concept. It delves deeply into how Ultimate's advantage state works and is just 9 minutes. So let's boil down what the core aim should be when cornering opponents: focus on option coverage, rooted in attacking where the opponent is rather than the opponent themselves in a noncommittal manner. When I say noncommittal, I mean in a way that doesn't lose too much frame advantage and stage control.
The key thing to note here is noncommittal options. K. Rool, being a superheavy, doesn't have too many of these, but they're significant enough to make it easy once he has the opponent cornered. Let's review our safest options:
Tomahawk / Short Hop Fast Fall - We have 2F (soft) landing lag when doing this thanks to our ridiculous fall speed, plus every single aerial option as a potential mixup. This is amazing at baiting out options, and by reeling back, we can keep the opponent out with relative safety. Remember, our aerials have unspeakable shield safety unlike most heavies, and we can abuse this all day every day. When that video goes over how MKLeo jumps back to gain stage control, think of how you can apply this.
NAir/FAir - -4 and -5 on shield respectively with a good landing, allowing us to dash back with impunity. Remember what the video says about how to pressure shield properly, we can do this effortlessly. FAir, in particular, has a gigantic hitbox and a disjoint, effectively dashing back for us when we space. Thanks to this, we can wait for the opponent's crap out of shield option and punish it without dropping any frames.
Jab - Our Jab has a FAF of 23, our fastest grounded option, plus the option to continue it at any point. Thanks to the large hitbox by Jab standards, we can actually space against shieldgrabs and/or dash back. The option to continue can also allow us to catch hasty out of shield options, which often gives the implication that the player we're fighting is the button-happy type.
I would consider other options to be a bit too committal, but make no mistake, they're still great. It's just not what you use early into Game 1 when you haven't sussed them out yet. This is your starting loadout, add to it as you go and you'll do just fine. Don't overcommit, take what that video said into account and apply it.
Ledgetrapping
While it's the same YouTuber and player, this is still a fantastic guide that goes hand-in-hand with the cornering guide. Watching both before reading this is highly recommended to understand what I'm putting forward, and for visual learners, this is of great assistance as well. I also suggest watching GimR's Ledge Intangibility Deterioration video, as it helps immensely with progressively strengthening your ledgetraps as they go on.
The main aim when ledgetrapping is simple: keep resetting the situation to build damage. Ledgetrapping is an extremely powerful strategy, especially when factoring in this game's brutal jostling mechanics. With K. Rool's gigantic size, this actually works to his advantage: he's like a wall, and getting around him in this state is genuinely difficult. You can't even cross him up without an aerial or something like Cloud's DTilt up-close. This actually makes K. Rool very good at covering jumps, especially with his NAir, which I'll go over in just a minute. To put it simply, you can't really jump past K. Rool.
K. Rool has a variety of ledgetraps, and thanks to the sheer size of his moves, he has numerous ways to put the opponent down. Here are some of his more notable viable options. This won't go over all of them, as there's a lot, but it's enough to get you well on your way to succeeding with the king!
NAir Ledgetrapping
You've likely seen KirbyKid mash the absolute shit out of NAir by the ledge in the past, and probably even copied it with success. However, you likely haven't looked at why it works. The main reason it does work is because of the landing lag on NAir: it's a mere 9 frames. This allows for a buffered dash, and when mashing SHFF NAir, the window to escape is quite small. Thus, it's very easy to react to getup options and chase the opponent down, simply because of NAir's noncommittal nature. With the armor factored in on top of this, you can see how difficult this is to actually contest. Don't just mash NAir though, play reactively. This ledgetrap works better when conditioning the opponent to contest NAir and doing timing mixups. Throw in some movement, maybe a FAir or two, and watch the opponent's ledge intangibility.
FAir Ledgetrapping
This is usually done on a platform near the ledge, such as on Battlefield, Pokemon Stadium 2, or Yoshi's Story. Because FAir covers an entire platform in length, dropping through one enables K. Rool to cover everything under it. If the move is spaced from around the middle, this covers neutral getup, roll, and whiffed ledge attacks perfectly. Additionally, you can jump with FAir to punish any jumps. This can be very difficult to contest if your reaction time is on-point. If FAir happens to whiff or hit shield due to a bit of a blunder, it's safe enough to the point that you can often get back into the game quickly. Remember, the landing lag on this move is a mere 11 frames, it doesn't mean much.
Reverse Crown Ledgetrapping ("The Chirori Trap")
QuackAttack figured this out early into Ultimate's lifespan, but Chirori popularized and advanced it in Japan in late-2020. There's a lot of history to this trap among higher-level K. Rool players, but few lower-level K. Rool players know about - let alone exploit - this interesting option.
This revolves around using a Crownerang in the opposite direction to the opponent from close to centre stage, then jumping onto a platform or just over the crown in general.
What this does - due to how Crownerang tracks K. Rool - is have it slowly dip past the ledge while still maintaining its hitbox. As a result, it covers almost all grounded options while K. Rool can cover everything else. This means that roll, neutral getup and getup attack can all be covered at some point, exemplifying K. Rool's already solid ledgetrapping.
The main disadvantage to this ledgetrap is that it takes 2+ seconds to set up, which in practice, is a whole lot. As a result, not only is this easily telegraphed (albeit without much they can do), but it's also difficult to time. The setup required is absolutely worth it and should be taken into account, but it will take some practice to do well.
It should be noted that unlike in most videos, Blunderbuss isn't the only option when jumping onto the ledge. Waiting and reacting to Crown hitting the opponent to kill confirm is viable, as well as using options like platdrop FAir. There is a lot you can do with this ledgetrap, and it's really all up to your imagination to figure out your favourite options. Catch their roll with DAir/FAir, BAir them when Crown hits, do whatever you damn well please.
DAir at Ledge
While not quite a ledgetrap since this literally just kills them, DAir has an important quality that makes it the premier way to punish the opponent's Ledge Intangibility Deterioration. Its hitbox goes way beyond the ledge and lasts a good while, including the early window with the meteor smash. Because of this, opponents stalling on the ledge will be forced to re-grab or - if at like 70% - simply die.
It should be noted that this hits every ledge-grab and can even 2-frame. Hell, it can go beyond 2-framing and simply hit opponents recovering. Practising this is crucial, especially against characters that have sound cues like Palutena's Teleport.
If you muck up a DAir at ledge and the opponent grabs it, you can often transition to a NAir Ledgetrap and punish their quick getup options. This move demands respect and players will often try very hard to get off. I mean, who'd risk another run-in with the Smash incarnation of the Grim Reaper?
Edgeguarding
Before I even discuss edgeguarding, I want to address a common mentality mid-level players have with it: edgeguarding is inherently one of the biggest commitments you can make in Smash. This implies you know your opponent's recovery route and are going to end their stock early for it. You are willing to forgo complete stage control - DAir at ledge be damned - in an attempt to take their stock. If you miss, you lose all control and are now at a disadvantage. So, with this in mind, you now understand that when you go to edgeguard, you need a plan. Don't just fling out there with NAir to try and score a gimp, you need to see what the opponent is actually doing. You have to watch them and evaluate whether it's necessary to make such a commitment. Remember that you have one of the slowest recoveries out there: if you miss you're in deep shit mate.
You got all that? Good. Because that mentality is all you need to edgeguard successfully: watch your opponent, time your attack, watch them die.
K. Rool's edgeguarding is among his flashiest aspects, I'm sure you've seen players get some amazing clips on people. The best part is that it's not just flashy: it's bloody great. The dopamine release you've got from timing that BAir dunk is unlike anything you've ever experienced, yeah? 'Corse it is, mate. If you want to edgeguard optimally though, with K. Rool, you honestly should just NAir offstage most of the time, or FAir if you want to guarantee an early stock. A lot of his aerial attacks are ridiculously committal, using two FAirs eats a double jump, BAir and DAir can kill you for fast falling, UAir is helping them more than anything...NAir is the only one that can be used more than twice reliably. This isn't to say it's bad, it's just limited: NAir is borderline broken for edgeguarding and FAir is FAir, so you're still golden and are gonna take a ton of stocks this way.