When the special attack button is pressed, Kirby will inhale and create a vortex of wind in front of him. Kirby will not stop inhaling until the button is released. Characters near the vortex will be sucked inside Kirby, who will bloat up with the character inside of him (which thereby increases his weight). In the original Super Smash Bros., he is immobile in this state, but in all following games he can walk extremely slowly and even jump a short height. At this point, Kirby can swallow the victim by pressing down or the special move button, copying their neutral special move and popping the victim out of himself. Kirby can also spit them out as a star without copying their ability by pressing the attack button. Spitting deals set knockback to the victim while sending them a fixed distance forward, and those hit by the star will take damage and moderate vertical knockback (much more in SSB4). Swallowing the enemy does more damage than spitting them out, but spitting is more easily repeatable.
In all games prior to Super Smash Bros. Ultimate, Kirby is unable to inhale projectiles. In Ultimate, Kirby can inhale certain projectiles; upon doing so, Kirby can either swallow it to regain health, or spit it back out as a star.
After inhaling a character, pressing down or the special attack button will make Kirby swallow them and receive a corresponding Copy Ability, which is the victim's neutral special move. Kirby receives a unique hat depending on the Copy Ability received, such as Mario's hat if he swallows Mario. After a short period of time, Kirby may lose his Copy Ability by being attacked, and he will also lose it upon being KO'd. He can also manually discard it by taunting. If a Kirby attempts to copy another Kirby that has no Copy Ability, the swallowed Kirby will pop out normally, though a different sound will play (which plays in the Kirby games when he copies an enemy with no ability). If a Kirby swallows a Kirby with a Copy Ability, he will steal it away from them.
Because Kirby is smaller than most of the characters he inhales, his copied moves are sometimes inferior versions to theirs due to his lower reach and smaller hitboxes. This is typically applicable for physical neutral special attacks, as exemplified by moves such as the Giant Punch, as well as certain projectiles; for example, Kirby's lower release point causes Mario's Fireballs to bounce faster and therefore last a shorter amount of time. On the other hand, his small size and unique moveset allow for interesting setups with some copied moves. For example, Kirby's relatively lower height prevents some characters from ducking under shots fired from projectiles such as Blaster and Bullet Climax. He can also laser lock more characters than Falco can for similar reasons. Some abilities are modified from the original copied character, simply because they require a part of a moveset that Kirby doesn't have. Some examples include Olimar's Pikmin Pluck, where Kirby plucks a Pikmin and immediately throws it as a projectile before they disappear, or Rosalina and Luma's Luma Shot, where Kirby shoots out a Luma to hit the opponent before the Luma immediately disappears.
In earlier Smash games, a majority of Kirby's copy abilities are identical or at least extremely similar to their original counterparts, although some have direct differences to their original counterparts (outside of Kirby's different dimensions/attributes). This is the case, as Kirby's copy abilities all have their own animation/hitbox data found within Kirby's character files. This meant that if the developers wanted to change a character's neutral special move, they would have to do the same with Kirby's versions and in some cases, Kirby's versions did not see those changes. An example of this which can be seen in Smash 64, Melee and Brawl is with Falcon Punch. In Smash 64, Kirby's Falcon Punch sweetspot deals 1% more than Captain Falcon's making it slightly stronger (although Kirby's aerial version does not deal extra shield damage). In Melee, Kirby's Falcon Punch does not have a mid hit and its sweetspot and sourspot are positioned differently from Falcon's (with Falcon's sweetspot being closer to him while Kirby's is further away from him). In Brawl, Kirby's Falcon Punch has smaller hitboxes than Falcon's; however, it has higher knockback scaling (keeping its values from Melee), making it stronger than Falcon's.
In Smash 4, the hitbox data for copy abilities are now loaded from the original fighter rather than Kirby having his own hitbox data for his copy abilities. This was likely done as it was easier for the developers, since if they had to change any character's neutral special, they wouldn't have to worry about making those changes to Kirby's version, as the changes would be made automatically. As a result, whenever a character's neutral special's hitbox properties got changed in a patch, Kirby's received the same changes as well with no input from the developers. Because of this, most of Kirby's copy abilities are identical to their original counterparts with a select few exceptions. Some attributes (such as animation length outside of frame speed multipliers, interruptibility and intangibility) are still tied to Kirby, so in theory, Kirby's copy abilities could still have a differing amount of ending lag or intangibility to their original counterparts.
As of Ultimate, most of Kirby's Copy Abilities are around 20% stronger than the character originally copied. However, there are a few exceptions to this change, such as Monado Arts, which don't boost Kirby's stats as much as Shulk.
Copy Abilities gained from opponents in game modes with off-loading fighters (such All-Star Mode) are lost once the corresponding character is off-loaded.
After inhaling a character, Kirby can spit them out ahead of him as a star by pressing the attack button, dealing damage to the spat character and potential collateral damage to bystanders. In Smash 64, characters spat via Inhale deal 6% damage to bystanders. Starting in Melee, the damage dealt by a spat character is loosely based on their weight; this remains the same between the NTSC and PAL versions of Melee despite differences in weight. Both Kirby's and Dedede's Inhales operate the same in this respect.
Note: For accessibility purposes, Ultimate data percentages have been rounded.
Main article: Item-swallowing
Just like King Dedede's Inhale and Wario's Chomp, Kirby can swallow items using Inhale, starting in Brawl. Inhaling certain items such as Food or Superspicy Curry will take effect promptly after being eaten. In addition, Kirby can inhale any item on the screen, automatically swallowing and keeping other characters from using it. In Super Smash Bros. 4, this heals Kirby by 1%. However, Poké Balls, Mr. Saturn, and other select items cannot be swallowed. Large items such as crates take a longer amount of time for Kirby to digest, and Kirby can neither move nor attack until they are fully swallowed. If Kirby inhales an explosive such as a Bob-omb, he will receive 5% damage.
Starting with Super Smash Bros. Ultimate, Kirby is able to inhale certain projectiles. If the projectile's hitbox that Inhale detects has a radius of 5.0 or greater (for comparison, Kirby's shield has radius 8.2), he can hold the projectile in his mouth and spit it out as a star, while if it is smaller he swallows it and gains some healing. The following is a list of projectiles Kirby can inhale, and what state he is put into after inhaling them. He cannot inhale another Kirby's star, as it will go straight through the move and hit Kirby.
Inhaling non-playable characters
Kirby cannot gain Copy Abilities from swallowing enemies, bosses, and thus all non-playable characters aside from Giant Donkey Kong and Melee's minor bosses. However, Kirby can still inhale and swallow members of the Multi-Man teams, Metal Mario in 1P Game, and the various enemies appearing in Smash Run and Master Fortress. Kirby can inhale and swallow whole enemies from Adventure Mode, as well as Waddle Dees and Doos thrown by King Dedede. In the Subspace Emissary, the vortex created by Inhale pulls in false characters and deals repeated damage to the Subspace Army.
Main article: Kirbycide
In Super Smash Bros., Kirby can jump off the stage and inhale an opponent, then fall off the stage and force a KO. In Super Smash Bros. Melee, Super Smash Bros. Brawl, and Super Smash Bros. 4, Kirby is capable of slowly walking around the stage while carrying opponents in his mouth, or swallowing a foe while slightly off-stage. This allows for some forms of Kirbycide, wherein Kirby jumps off the edge with someone in his mouth and releases them at a distance or position from which they are unable to recover, and force a KO. One may Inhale at the last second for a K.O. (usually during Time Mode for an extra point) and may survive due to Kirby's tall recovery.
Special Move customization was a feature exclusive to Super Smash Bros. 4. These are the variations:
Inhaling and spitting has been Kirby's trademark attack since Kirby's Dream Land, but it was not until Kirby's Adventure was he able to swallow an enemy to copy their attack. Kirby Super Star introduced unique hats indicating different Copy Abilities. A single attack from an enemy or damage incurred from the environment was usually enough to make Kirby lose his Copy Ability, though later Kirby games feature entire health bars instead of health points, so it is possible for him to occasionally keep his Copy Ability even after being damaged. After Kirby loses his Copy Ability, it takes form of a star bouncing around the screen. Kirby can inhale and swallow it to regain the ability before it disappears after it contacts a hazardous surface or enough time passes.
One of Kirby's custom moves, Ice Breath, is based on his Ice ability, which first appeared in Kirby's Adventure.