Kirby is given a choice between the Beam and Ice abilities before proceeding to this fight.
Inside the throne room itself is King Dedede, standing before a strange, flashing machine. Dedede fights as he always had, though he flinches a lot more when hit (likely to make him easier as a first boss). Defeating him completes the stage, and the level, and also nets Kirby a Boss Battle Badge. If this was the first time Dedede was defeated, a cut-scene is also triggered here, which then leads directly to the first stage of the next level, Nature Notch.