Ninja

Ninja is an ability primarily obtained by absorbing a ninja type enemy, such as Bio Spark. It allows Kirby to perform one of several ninja-type attacks and moves.

Kirby Super Star / Kirby Super Star Ultra
In Kirby Super Star and Kirby Super Star Ultra, Kirby can obtain the Ninja ability from Bio Spark. With the ninja ability equipped, Kirby can then call Bio Spark as a Helper. With the ability equipped, Kirby's visual appearance changes by him turning a darker shade, and wearing a hat similar to that of the Stone ability.

Kirby: Squeak Squad
Ninja is obtainable from Bio Spark and Spinni's shurikens in this game. The move-set is a little different, in that Kirby does not have a counter move, but can charge energy and release it in a big wave if he has the Ability Scroll for Ninja. He is also able to walk on the surface of water.

Kirby's Return to Dream Land
Ninja returns as an ability in Kirby's Return to Dream Land, acquirable by swallowing a Moonja. Many new techniques are available in this iteration.

Kirby: Triple Deluxe
Ninja returns as an ability in this game, unchanged from its appearance in Kirby's Return to Dream Land. It is still obtained from Moonja. It is also one of the abilities available in Kirby Fighters.

Kirby Fighters Deluxe
Ninja returns as one of the selectable abilities in Kirby Fighters Deluxe.

Kirby: Planet Robobot
Ninja returns, along with Moonja, in this game. It is still unchanged from its previous appearance in Kirby: Triple Deluxe.

Kirby Battle Royale
"When you use your Ninja ability, you'll have lots of fierce moves! With those, you can unleash quick attacks for a decisive win."

- Knuckle Joe's comment in Kirby: Battle Royale Ninja is one of the abilities on offer in this action-multiplayer title. In this title, Ninja Kirby is able to create a decoy of himself, which will explode on contact with a foe, and he can also create a huge fiery explosion using a stealth bomb.

Unlike other abilities, Ninja has a total of three charge-up moves.

Kirby: Star Allies
Ninja returns in this title, though this time it is once more provided by Bio Spark, who also represents the ability as a Friend. Ninja can be augmented by elements such as Blizzard, Bluster, and Zap.

Super Smash Bros. for Wii U trophy
"Making his debut in Kirby's Return to Dream Land, the Moonja enemy looks about as ninja as you can get. If you copy its ability, Kirby can become a master of the ninja arts! With a variety of useful skills like Knife Throw and Blossom Storm, you might want to remain a ninja forever!"

Trivia

 * In Kirby Super Star and its remake, Kirby Super Star Ultra, Ninja Kirby's 'Ninja Kick' can be cancelled by hovering. By doing the loop of Ninja Kick-Hover-Air Bullet, Kirby can save his horizontal momentum from Ninja Kick and move very fast in the air, his action of continuously spitting Air Bullets somehow resembling the effect from the Mint Leaf. This game mechanic of saving momentum, while useful on TAS speedruns on those games, is not present in games following Kirby's Return to Dream Land.