When performed, Kirby opens his mouth and inhales, sucking nearby opponents into his mouth. While an opponent is in Kirby's mouth, Kirby can walk around and jump with them for a short period of time before they escape automatically. Kirby can also spit them out as a star with the standard input, dealing 10% damage to the opponent. Most notably, he can swallow them with the down input or special input, dealing 6% damage to the opponent. By swallowing an opponent, he absorbs their standard special move as a "Copy Ability" and can use it himself as his standard special move instead. For each ability he has, he will gain a different hat allusive to the opponent he absorbed; obtaining Mario's cap, Mega Man's helmet, Lloyd's hair, etc. (see below for a complete compilation of revealed Kirby Hats). Once an opponent's standard special move is acquired, the player can use a taunt to discard it and revert to Inhale. It will also be discarded if Kirby is KO'ed or damaged enough.
Kirby will be able to use the Mach Tornado and will have Meta Knight's mask. However, unlike Meta Knight's mask, which has yellow eyes due to Meta Knight having white eyes, Kirby's mask has green eyes due to Kirby having blue eyes.
Kirby will be able to use Paralyzer and will have Zero Suit Samus's ponytail.
Inhaling and spitting has been Kirby's trademark attack since Kirby's Dream Land, but it was not until Kirby's Adventure that he was 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 it, it takes the 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.
Kirby after using Inhale and having a character inside of him.
Kirby does not have this ability in the original Super Smash Flash due to Cleod9's inability at the time, to properly code copy abilities. In compensation, he instead gave Kirby the ability to tag out with Meta Knight at any time.
Prior to v0.3a of the demo, Kirby did not have a hat after he inhaled an opponent, plus he did not inhale the opponents at all; instead, he could inhale a small star from them.
Kirby was also able to inhale and swallow Final Forms and use their powers; this was changed in order to prevent cheapness.
For the rest of the newcomer fighters in Super Smash Flash 2, Kirby did not have his own voice such as "Demon Fang!", "Rasengan!", "Pistol!" etc.; however, he still used the official voice clips from the official Super Smash Bros. games.
This special move has given the developers a lot of work to do due to needing to sprite the hats to represent what power Kirby possesses. To go along with this, if something were to change to a character's standard special move then the devs would have to work on Kirby's as well.
Also, when Kirby has a hat and performs certain complex animations (especially ones that cause Kirby to spin, like his up smash and his aerial side special), his hat will temporarily disappear and an Ability Star will hover around him until that animation is finished.
In previous versions of SSF2, when Kirby is using a palette swap, his hat will be the normal color. However, when he uses his copied move, his hat will change color.
When copying Donkey Kong, Samus, or Mr. Game & Watch, Kirby's copy ability looks different than his appearance in official Smash Bros games due to the limitations of the engine not being able to accurately represent the originals, which covered his entire body.
When copying the Fighting Silhouette Team, Kirby will still gain the ability of the character the silhouette is mimicking despite the silhouettes not being able to use the special move copied themselves. This is unique among the Enemy Teams, whereas with all of the official ones, attempting to copy them would simply fail.