Special move

A special move is any move that is activated by pressing the special move button (O by default). They were first introduced in the  series in Super Smash Flash 2. Special moves include the standard special move, side special move, up special move, down special move, and Final Smash. All standard special moves can be used by, because of his standard special move: Inhale.

Uses
Most special moves are often a character's signature moves, such as 's Falcon Punch and 's Judge. Special moves have many different uses, and may differ from each other in effect. Most projectiles can only be launched through special moves, such as 's, and most up special moves are used as a third jump to recover. However, most moves that aid in recovery render the user helpless when used in the air.

Final Smash
A Final Smash is a special type of special move that can be activated by obtaining a Smash Ball through breaking it using attacks. It is activated by pressing the special move button, like the player would when doing a standard special move. A Final Smash often does an attack which deals high amounts of damage and knockback. However, some Final Smashes involve the player transforming into an advanced form, where their attack's power are often increased. This is called a Final Form. A Final Form that does not have a complete moveset, or has about 1-3 attacks is called a Semi-Final Form.

Trivia

 * Donkey Kong and Peach's are the only specials that cannot be performed Mid-air.
 * Similarly Naruto's Standarad special can be performed but functions differently in mid-air.