From Kirbypedia

Combo abilities, or mixing, is a relatively new thing in the Kirby universe, where two different copy abilities are combined to make a new one. The first appearance was Kirby 64: The Crystal Shards.

Kirby 64: The Crystal Shards

See KRR for a full list with images!

• Missiles - Bomb + Bomb - Kirby's mouth will open wide, and he'll launch three enemy-seeking missiles.
• Fireworks - Bomb + Fire - Kirby will 'explode' into a shower of fireworks multiple times as he flies around in the air.
• Dynamite - Bomb + Stone - Kirby will set down a few sticks of dynamite with a timer. If Kirby isn't ducking under his miner's cap when they explode, he'll be damaged too.
• Ninja Bomb - Bomb + Cutter - Kirby throws a lightning-fast shuriken which will stick into enemies and obstacles and explode.
• Exploding Snowman - Bomb + Ice - Kirby will turn into a harmless looking snowman with a Bomb under its hat, that explodes if an enemy touches it.
• Exploding Gordo - Bomb + Needle - Kirby takes on the form of the enemy Gordo, floats around and explodes to send out a shower of needles.
• Light Bulb Blast - Bomb + Spark - Kirby turns into a cute walking light bulb that will explode.

Kirby Squeak Squad

Thanks to the Copy Scrolls, mixing abilities returns on a small scale. If Kirby has two ability bubbles of specific types, if he swirls them around until they've changed all the colors of the rainbow, they will be combined. This adds attributes of another ability to the attack method of the base ability.

Sword

• Ice Sword
• Fire Sword
• Spark Sword

Bomb

• Ice Bomb
• Spark Bomb

With other abilities, the Copy Scroll allow Kirby to gain elemental powers from the environment the power is used on instead of mixing it with other bubbles. Snow yields ice, magma grants fire, and electric flames add current.

Tornado

• Ice Tornado
• Fire Tornado
• Spark Tornado

Wheel

• Ice Wheel
• Fire Wheel
• Spark Wheel

Kirby Copy Abilities:

Cupid - Animal - Backdrop - Ball - Balloon - Baton Twirling - Beam - Bomb - Bubble - Burning - Clean - Cook - Copy - Crash - Cutter - Fighter - Fire - Freeze - Galaxia - Ghost - Hammer - Hi-Jump - Ice - Iron - Jet - Laser - Light - Magic - Metal - Mike - Minimum - Missile - Mirror - Needle - Ninja - Paint - Parasol - Plasma - Sleep - Smash - Smash Bros. Abilities - Spark - Stone - Suplex - Sword - Throw - Top - Tornado - UFO - Water - Wheel - Wing - Yo-yo

Final Weapons:

Star Rod - Love-Love Stick - Rainbow Sword - Star Chariot - Master - Triple Star - Block