The Electroplankton universe (エレクトロプランクトン, Electroplankton) is one of the many unique universes represented in Super Smash Bros. Brawl and Super Smash Bros. Ultimate. The universe consists of only a single title.
Electroplankton initially released for the Nintendo DS on April 7, 2005 in Japan and early 2006 worldwide. Satoru Iwata explained in a 2005 interview that the game was the idea of Toshio Iwai, who developed the entire game by himself. This is why his name is printed on all packaging and marketing.  It is less of a game and more of a music creation tool. There are ten different stages, or "instruments", in the game: Tracy, Hanenbow, Nanocarp, Beatnes, Rec Rec, Lumiloop, Luminaria, Sun Animalcule, Marine Snow and Volvoice. Each instrument uses different sounds that the player can experiment with. The game is split into two main modes: Performance and Audience. Performance mode involves the player directly interacting with the stage and the plankton to make various noises and music. Audience mode cause the plankton in the stage to act on their own for the player to watch and listen, though they can still be interacted with.
The game was indirectly rereleased in 2009 for DSiWare. All ten instruments were split up and sold separately for 200 Nintendo Points each. This was a cheap alternative for those that only wanted a portion of the game.
In Super Smash Bros. Brawl
In Super Smash Bros. Ultimate
A Hanenbow appears as a spirit.