Here's something you oughta know...

King Knight is a hefty all-rounder who has stats on the slow side, but makes up for it with tricky projectiles and fast, powerful moves!
If the in-game (i) button doesn't satisfy you on information, here's some tips and tidbits for helping you make the most of your royal stature!
Do note that this won't cover Every move, just ones with certain things I'd like to point out. Experiment with moves yourself and see if you can find things!

King Knight was made using a "test" template of sorts that I've concocted, and thus he has a few special rules to him. These aren't specific traits for him specifically, so I'll be referring to the affects with "This Character" for the most part.

-This Character bounces off the floor while in hitstun, instead of going into crash states. This took a lot of ironing out, and hopefully no longer sends this character to the moon, but it's pretty cool. You can still tech the landing impact, of course!
-This Character automatically jumps when grabbing a ledge! You'll have a bit of invincibility and a small window to act out of the jump, but your air control is restricted.
-This Character won't go into freefall out of Air Dashes! For King Knight specifically his airdash is very short, but the range of swifter characters could be different.
-This Character only has Forward Throw and Back Throw, but Up/Down throw will redirect you to them.

I may be forgetting some things, but this is most of the important stuff. Got it? Good, let's continue.

Jab is a single hit with a hefty amount of hitstun. If you tap the button again however, you can go into a slapping fury! Once the flurry starts, you can just hold the button to keep slapping.

This move's horizontal range leaves... a lot to be desired, but it makes up for it by having a potent anti-air scoop.

King Knight, legally, isn't a doctor. But that hasn't stopped him before, and it isn't stopping him now either; this move starts out weak and gets stronger as it lingers.

This move was originally going to be Up Tilt, inspired by the fight against King Pridemoor, but the King Knight moveset for Rivals of Aether made by NewFoundAbility, FuZZ_lol and batit the plant is just too fun to use Up Air with, so I pretty shamelessly yoinked it. There's a few other moves with similarities to the RoA King Knight--such as Down Tilt and Forward Air--but those are more coincidental. Up Air specifically is a yoink from them, shoutouts to them.

A decisive finisher with the Gyro Boots! While you can't climb walls with it here, if you hit the initial spike of this move you'll bounce off peoples' heads! Isn't that fun?

This aerial utilizes the Turn Coat! As the name implies, you'll get flipped to face the other way when exiting the move. When you see a barrier at your cape, that means you can reflect projectiles that come your way! A reflector positioned behind you sounds unorthodox, but I'm sure there's some uses for it..

The rats are loyal 'til the last! Once it lands it'll go into action, deploying it's not-so-safety bomb on any enemy it touches, and the rat will automatically hop if running off a ledge.
While the rat is active, you can tap Neutral Special again to Command it, which will turn it around to start running the other way. You can also either double-tap or hold Neutral Special during the call animation to dismiss it early!
If you don't know what your rat is up to when it's offscreen, keep an eye on your HUD; there will be a small display of what your rat is up to and what direction they're going!

You can also use Side Special into your rat to detach the bomb and fling it as a projectile! This also gives you bonus height on your initial bounce! There are other things you can do with Side Special and the rat, too. Try experimenting!

King Knight's bread and butter! With a small bit of armor at the initial barge, King Knight will bounce off of walls and foes alike and spring into the air upon hit.
On your initial spin after an impact, you're mostly helpless--the only thing you can do is move around and use Up Special. You can't even grab the ledge! But if you manage to bounce off of somebody's head, you'll get sparkles indicating that you're fully actionable! Do a follow-up right away, bail out for a recovery or try and chain more bounces? The choice is yours..

If you don't, or don't want to, hit someone with your shoulder, you can press the Special Button again to do a roll!
If you do this at the start of the roll, or when holding Shield at any time, you'll do a lightning-fast tumble. While it may not have a hitbox, it's speed, momentum and low endlag can keep you light on your feet!
If you time it at the very end of the barge, when sparks are at your feet, you'll go into a superpowered charge! You'll be invincible for a brief flash, and the power combined with speed is a royal force to respect - but shielding foes will be a problem...

Take a lift with your trusty propeller rat! You won't have a hitbox, and the vertical distance has some room for improvement... but you'll get an extra hoist at the end of the move, and you can exit the lift with an attack at any time! ...just be aware that you'll go straight into Helpless after doing so.

Pull out your deck and pick a card! Press Up, Down, Left or Right to prepare a card face-down and end your turn. After a few seconds, the card will reveal itself and charge in the direction you ordered!
Either Horizontally or Vertically, depending on the card you chose, the Joustus Card will attempt sending foes in your direction depending on your position at the time of impact. Think you have the brains to match your brawn?

King Knight has a lot of taunts! There's a taunt for holding Neutral, Up, Down and to the Side on the control stick while pressing the taunt button.
There's also an extra taunt if you hold assist, but it's quite showboat-y... only use it if you don't think anyone will punish you for it, I'd recommend.