Ultimate Dedede is a boss in Kirby: Cozmic Adventure. Like all the ultimate bosses, Dedede can only be fought after completing all modes 100%, unlocking the Ultimate Arena
Ultimate Dedede looks like regular King Dedede at first glance. However, his regal robes have been replaced with red and yellow armor. After the player halves his health, he grows stronger and puts on Masked Dedede's mask.
Dedede's primary attack is to jump up and slam his hammer on the ground, just like in Epic Yarn. However, the hammer is now electrified, so instead of creating stars, it generates an electric shock wave that travels along the ground. He will often follow this attack with another one, in which Dedede spins around with his hammer, just like Hammer Kirby. Another attack he has is where he opens his hammer. He will either shoot three small missles that home on Kirby, one large missle that doesn't, or a large stream of fire.
In phase 2, he has more attacks. He jumps in the air and places two packages. One contains a Gordo, the other contains either a random ability or food. They move around in a horizontal line, dropping when Dedede manages to hit them in an attack. Both items bounce two times before poofing away. His tornado attack has changed, too. He will actually hover above the ground, dropping when Kirby is below him. A new attack is he summons a unique Waddle Doo that fires plasma bolts, called a Waddle Doof. It gives Plasma if eaten.
The whole time, Dedede's battle arena is changing. He will constantly pound the floor and the player will fall to another floor. These include:
- A kitchen. A Waddle Dee with a chef hat is standing in the crowd. He will toss either food or bombs into the arena.
- An odd weapons facility. Two Shotzos line the walls.
- A furnace room. The floor is filled with lava that erupts when Dedede does his standard attack.
- A generator room. Four wires dangle from the celing, which periodicly fire bolts of electricity.
- Dedede's bedroom. The floor is extremly bouncy here.
- A bathroom. This floor is ironicly flooded and is under water.
- A ninja dojo-like room. Strange dummies pop out of the walls.