Wow, that second post needs updating...
R.O.B. as a problem matchup?
I keep forgetting. Why exactly is PS1 such a good stage for Kirby?
First of all, none of the transformations actually
hinder Kirby.
The edges give problems to some characters, but not Kirby. The size of the stage (boundary lines) are also a nice distance for Kirby.
On pretty much all transformation, Kirby can stand really close to the walls and use FC, and then projectile will go through them.
On the water transformation, he can uthrow Kirbycide under the windmill, and fighting with his back to the windmill can keep his floaty self alive longer.
On the forest transformation, he has the earthquake glitch on the right side of the short bush-thing to the far right. He can shark through the pass-through platforms.
On the fire transformation, he can do the campy FC thing I mentioned earlier on the left. He also has a dtilt semi-lock against the tall tree thing (semi-lock because Kirby is slowly pushed away, but he can still rack up quite a bit of damage). Uthrow on top of the tree KO's fairly well. The tree can help him survive longer, and he can shark through the platforms.
On the rock transformation, he has inescapable jab- and dtilt locks in the depression in the middle. He can camp with FC (again, as mentioned earlier) in the pit (ideally) or on the far left. Rock has good slides around this portion of the stage.
Because of the way the edges are, Kirby can use a dsmash and hit people directly under them and epicly stage spike them.
He has a Ninja Spike Lucario and ZSS on the edges. With proper timing, he can also NS an Ice Climber or Snake on the water transformation.
Finally, many characters are hindered by the changing terrain (Kirby's projectile is the only one awesome enough to go through walls, for example).