In my moveset concept for K. Rool, he's fast, aggressive and extremely heavy (just below Bowser in terms of run speed, standard frame data and weight), though his "discharge" mechanic means he has to slow down when he's in zoning mode. I imagine his movement would be akin to Dedede's down-b in that mode, in that he can move and jump while charging, just that his speed is stunted during the charge.
I'm not sure how that would work in practice, though. I guess there's a precedent in PM Snake or Smash 4 R.O.B.: a zoner and trap-setter with great stage control options and decent mobility and speed on their close-range moves. If the discharge mechanic means he's weak by default and very powerful when fully charged, then his close-range moves would be used as a last resort or to keep troublesome rushdown fighters off of his case. In that sense, having fast and reliable close-range moves
The thing is, theory doesn't necessarily equate to practice. When the game first dropped, people were convinced that Bowser was unbeatable: a fast, weighty character with immense power and heavy armour? Then the meta developed and people realised that, hang on, Bowser has a ton of weaknesses that hold him back from being the top-tier terror we thought he'd be. Even though he has a ton of good options in theory, when you put everything together and test it out, it doesn't really work as a cohesive set.
That's why it's dangerous to examine moves in a vacuum. In theory, every character is great. You can detail any set out of context and make it sound jank (Ganondorf can kill in two hits but he needs to get the hard read or he's a sitting duck! Palutena has twelve unique moves but half of them are awful and her default set is near-useless!), yet in context, it can turn out to be underwhelming. K. Rool may sound intimidating in theory - ye gods! A fast, weighty zoner that can fight at close and far range! - but he could very easily fall apart when faced with a certain playstyle. I imagine reflectors would wreck him, while it'd be very hard to play catch-up with a character like Sonic or Sheik when you're essentially a giant mobile hurtbox.
In that sense, having a few reliable close-range moves is, debatably, necessary for K. Rool. Even an expert zoner / trapper like Snake or R.O.B. would crumble if they couldn't hold his own in a boxing match; plus, if R.O.B. has taught us anything, it's that having a huge hurtbox is a very dangerous weakness in any matchup.
In theory, K. Rool is the most broken character in the game, especially with the discharge mechanic: Bowser's weight, speed and power with Villager's projectile game? And he can charge his moves to become even stronger? JANK! JANK! JANK! JANK!
And then you stop and consider just what that means in practice:
- Huge hurtbox makes him combo food for smaller, quicker characters
- Focus on projectiles means he's easily countered by reflectors
- Discharge mechanic needs time to set up and can hurt him if he's reckless
- Traps also need time to set up and require good knowledge of the stage
- Close-range moves are strong and have good frame data on startup, yet enough endlag to nullify spam
- Even with a good recovery, his weight and size would make him easy to gimp
tl;dr - K. Rool would be broken as **** in theory, with enough noteworthy drawbacks in practice to keep him from being overpowered. Maybe about mid / high-mid-tier.
tl;dr pt. 2 - Max size / weight Mii Gunner. Try it and tell me it's jank.