post edited with transformations I forgot
How can you not know how to do the Stone glitch? Just turn into a Stone the middle/upper left part of the right side, either on the ground or from the air. I'm not sure if you can fall off the stage if you transform too far to the right. And this only works on the right ledge, and I think another random part or two of the stage's transformations.
For the stage itself, it's actually really good for Kirby. He can take advantage of most of the transformations pretty well, though I personally like some of them less than others. I find the wind-blowing guy to be annoying, for example.
on the left: pretty good for Kirby. You can Stone someone pretty easily if you're on the head, and they're stuck to the right of the head.
roller coaster thing: annoying, but Kirby can make use of it. I wonder what would happen if you upthrow through the hitbox? Kirby is invincible, but it might hit his opponent...
edit: what fromundaman said. That's what I thought happened: Kirby just kind of stops in midair, and the opponent gets hit by it.
fire: pretty annoying, but each hit only does 1% damage so whatever...
whale: it's ok. Stone can slide around, so you can use it with less chance of being punished. Stone glitch might work on the right part of the spout's water, I don't know, I haven't memorized all the Stone glitch spots in this game ._.
boxes: can be annoying to me, but overall not too bad. I think Final Cutter can go through the walls, at least if you're on the inside. Not sure.
bullets (or rockets or whatever they are): I hate these things O_O inhale->starshot into them could work pretty well...or you could Bair someone or fsmash them into it. Again, I wonder what happens if you Upthrow through one....
wind blowing guy: ANNOYING. (imo) ... maybe you could use it to your advantage. It might cause someone to mess up (like doing an aerial if you push them off the stage or something) I dunno.
Ladder thing: pretty basic. A long line on top, and a ladder on the right and left. You can taunt your opponent by climbing up one ladder, running across the top, and then sliding down the other ladder. That just looks funny.
Springs on the side: yeah, you can go through them with stone. That's about it...DON'T KILL YOURSELF by turning into a Stone right before they disappear, or you'll look like a noob.
house or whatever it is that creates ledges on the sides: prevents you from doing the Stone glitch. Darn.
spikes on the sides: makes for good laughs.
piranha plant: upthrow into it...heck, do anything into it. duh. it's pretty good.
the clock hands: you can do the stone glitch at a CERTAIN time on one of the hands, but it's not really useful. Good for combos and stuff.
These are all the ones I could think of. o_O
I actually don't use the Stone glitch much in an actual match, I feel like it's almost "cheating." Kinda like planking with MK.
But now that I think about it, it's not banned, and I've never seen anyone complain about it. I should abuse it as an edgeguard, to its fullest potential :]
I can just see myself winning a game because of the Stone glitch on a recovering Falco or whatever XD
Overall, 4 stars, possibly MORE if you really know how to use the stage changes to your advantage.