Kirby transforms into a rock, becoming impervious to damage and knockback for a short time, and quickly falls straight down. Kirby can still be taken out of Stone form by grabs or grab-type moves such as Yoshi's Egg Lay or Lucario's Force Palm. The transformation lasts for approximately 3 seconds, but the player can press the B button to end it early.
Offensively, Kirby can deal damage by using the move in midair and falling on opponents. When Stone is landed, it does excellent knockback, KOing most characters reliably under 150%; however, the move is rather situational as it is easily telegraphed and slow, making it a poor choice in most situations. Due to the sheer weight of Kirby in this form, he will slide off sloped surfaces.
In the first two games, Stone does no damage at all if used on ground. In Super Smash Bros. Brawl and onward, however, the attack produces somewhat unnoticeable sourspot hitboxes on Kirby's sides, dealing 14% damage with horizontal knockback. When Stone is used on the ground, Stone will always hit with this sourspot no matter where the opponent is, and Kirby solidifies several frames quicker to do it (compared to an air drop). Otherwise, all falling sweetspot versions of Stone deal 18% damage (20% in Smash 64).
In Brawl, the move is more powerful than in Melee, and it pushes characters away, even if used from the ground. However, if Kirby is hit with an attack that causes at least 30% damage, he will receive full knockback from it, but no damage. However, this means that a Mr. Game & Watch 9 will always defeat this attack.
In Super Smash Bros. 4, if Kirby takes 25% or more total damage while petrified, the deciding move will launch Kirby out of the stone, taking half the attack’s normal damage in the process. His Custom Stones absorb less damage.
In Super Smash Bros., Kirby can only transform into one type of stone. Since Super Smash Bros. Melee, however, Kirby will randomly transform into one of the following objects, all having the same properties:
In Brawl, there exists a glitch known as the Earthquake Glitch, which makes Kirby rapidly vibrate in place, producing hitboxes around him. This is achieved by using Stone on a downwards right facing platform that bends down at a 45° angle. It can be performed on both Stage Builder stages and the PictoChat stage, and while fighting Porky in Boss Battles mode, but it is generally attributed to PictoChat.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Stone is one of Kirby's Copy Abilities that originated in Kirby's Adventure, behaving in much the same way. Kirby Super Star introduced the detail of randomizing the transformations to various other types of objects, including a rare golden statue of Mario or Samus, as well as the mechanic of Kirby sliding down slopes while in this form. Kirby can attack while sliding down slopes in Stone form, but he cannot do this in Smash Bros. There are other minor differences between the way Stone functions in the Kirby games and in Smash Bros. In the Kirby games, Kirby can stay in Stone form indefinitely and cannot be knocked out of it through regular means; in Smash Bros., Kirby can only stay in Stone form for a limited amount of time, and can be knocked out of it with grabs or sufficient damage.