From Kirbypedia

English Name:	Mirror World Kirby
Japanese Name:	シャドーカービィ Shadoo Kaabii Shadow Kirby
First Game:	Kirby & the Amazing Mirror
Ability:	Variable
Category:	Regular enemy, Allies

A regular enemy and sometimes helper in the Kirby games.

Shadow Kirby is the Mirror World's counterpart to Kirby. It looks just as the hero does but is portrayed only in shades of gray.

Shadow Kirby is first seen after Meta Knight is trapped in the DImension Mirror by Dark Meta Knight. It follows him through the doorway into the Rainbow Route. While appearing at various points throughout Kirby's adventure, his final appearance is to aid the hero in the battle against Dark Mind. After the evil force is defeated once and for all, Shadow Kirby stays in Mirror World to defend it from any other invading evils that may come to the land.

Games

Throughout the game, Shadow Kirby appears in several locations, jumping out from hiding. He waits a short time, staring at the player, before either fleeing or attacking. He demonstrates the use of copy abilities, including Fire, Ice, none, and more, which he can attack the player with. A different behavior is fixed at each of his locations.

If he is inhaled and swallowed at a site that displays a power, the player gains that ability. If he is defeated with an attack, one of several possible items is left behind. Unlike most foes, Shadow Kirby does not respawn when a scene is returned to until the level is cleared.

During the battle with Dark Mind, in the second phase, Shadow Kirby appears to help the player by returning the Master ability shortly after the ability is lost.

Kirby Game Characters:

Main: Kirby - King Dedede - Meta Knight - Waddle Dee

Allies: Animal Friends - Gooey - Ribbon - Adeleine - Helpers - Other Friends

Enemies: Regular enemies - Mini-bosses - Bosses The Meta Knights - The Squeaks

Final Bosses: Nightmare - Dark Matter - Miracle Matter - 0 (Zero) - 0² (Zero Two) Marx - Dark Mind - Drawcia - Grill - Dark Nebula