Clu Clu Land is a video game for the NES game system. In 2003, it was rereleased on the e-Reader, an accessory for the Game Boy Advance, under the name Clu Clu Land-e. It is exactly the same as the NES game, the only difference being the absence of a 2-player mode. You could also reset the game at any time.
In Super Smash Bros. Melee
The main character of Clu Clu Land, Bubbles, appears in Super Smash Bros. Melee as a Trophy.
In Super Smash Bros. Brawl
Unira appears as an item. It stays in a ball until it is thrown, then it sticks its spikes out, damaging everyone who touches it. It absorbs attacks and makes the spikes stronger. However, if hit hard enough, it may receed back into itself allowing opponents to pick it up.
Unira also appears as a trophy.
Also the song Clu Clu Land plays on the Summit stage as a hidden song