^This basically confirms Kirby and Co. as planet busters (Dedede has no direct planet level feats but it's clear that he's on par with MK and Kirby)
The 1/4 of his actual strength feat is questionable though. Does the rest of the game reflect this?
Kirby on the warp star is FTL as shown here(Planet to Planet in seconds- 50-200 times speed of light):
http://gfycat.com/SlimInfamousDassie
http://gfycat.com/ImaginativeGoldenCrayfish
http://imgur.com/a/Eud1r (This one is questionably solar system to solar system)
BEST SPEED FEAT (Galaxy to Galaxy in seconds-minutes- Quadrillions/quintillions faster than light, possible outlier):
http://gfycat.com/InsignificantUnripeJabiru
Note that this is only when Kirby is the vacuum of space. He is MUCH slower when affected by earth's gravity and can only fly the star for a few seconds. But since he can breath in space and destroy planets this shouldn't be that much of a problem for him. Kirby is also invincible while on a warp star.
Ball Kirby flies FTL (note he needs to break the forth wall and have the player maneuver him, this counts as extra help):
https://gfycat.com/DemandingScornfulIndusriverdolphin
Here Kirby punches\drills with enough force/speed to punch straight through a small planet sized robot in a few seconds, putting him at around 1/50th of light speed without a warp star and after a punch (likely only works in outer space):
https://gfycat.com/PeriodicRemarkableBass
Jet Kirby can supposedly travel at Mach 5 but that's highly questionable and in game feats say otherwise.
Many Kirby power-ups attack at FTE and can do the Star Platinum FTE punching thing, but that's the full extent.
Claycia is an extremely high level reality warper and as shown above, can even create stars/galaxies. However, depending on how you look at it, the stars and galaxies aren't much bigger than a planet (depends on if you think it's to scale or not). I think its too questionable to consider.
Dark Nebula entering his second form causes a shock-wave that destroys the surrounding galaxies/stars (this is extremely questionable and should only be considered in an extreme highball of Kirby)
https://fat.gfycat.com/GrotesqueDefinitiveGreatwhiteshark.gif
Kirby pushes back an anti matter wave that was destroying many galaxies/stars(likely because of the properties of Kirby's star attack and not due to brute force, since none of the other characters can do this and Kirby only does it through the star exhale thing again, only for extreme highballs)
https://www.youtube.com/watch?v=pizpPBsP40k
Hypernova Kirby is described as a Veritable Black Hole, but in game feats say otherwise, only for high-balls should this be used.
Magalor is a universal threat but it's questionable if he could actually destroy it (only stated to rule/control it), I wouldn't consider it to be a canon feat, even if we highball Kirby. I still see Magalor as High Planet level like the rest of the top tier Kirby characters.
And yes, all of this scales to Meta Knight and Dedede (they have warp stars too and have near identical stats to Kirby)
So the Kirby characters, even when low-balled, are multi Planet level in Strength and durability, can travel at FTL Speeds while also being invulnerable to any thing in the Kirby Universe (planet level attacks), Can regenerate back to full health in a split second (Meta Knight can do this FIVE TIMES), Can clone themselves (helper, Only Kirby and Meta Knight can do this), Can stop time when unleashing a powerful attack (Crash ability, super abilities, Meta Knights tornado thing) Have Access to giant planet busting ships and planet busting robots (Meta Knight/Kirby only), and can change abilities at will (Kirby).
High-balled they have all of the above plus multi star level attack potency and durability, are quintilions of times faster than Light, and can turn into a black hole (only Kirby).
Can any other Characters match that?