Chibi-Robo cleaning up a stain using the toothbrush
The Toothbrush is a tool in the series.
Chibi-Robo! Plug Into Adventure!
At night, the toothbrush appears on the floor. Telly suggests that it could be used to clean stains. You can earn Happy Points for doing so. There are stains like mud from footprints, paws, or puddles, tears, and oil.
Chibi-Robo! Photo Finder
The toothbrush returns in this game. It can be used in Joshy Bear's request to clean the garage. It can clean the multicolored stains around the garage.
Chibi-Robo! Zip Lash
Though the toothbrush is not able to be used in this game, it briefly appears in the first cutscene when Chibi-Robo uses it to clean the ship.
Found on the episode "Chibi's First Story / In the Street"