Gearmos usually appear on planets with a large amount of trash. In Super Mario Galaxy, they mostly inhabit the Toy Time Galaxy, where two Gearmos each have a job for Mario. In these jobs Mario throws Bob-ombs at garbage, thus cleaning it up. If Mario does this for both Gearmos he can acquire two Power Stars. A Gearmo can also be found in the Engine Room of the Comet Observatory.
Similarly in Super Mario Galaxy 2, Mario is also put in charge of burning up trash with Bob-ombs or flames as Fire Mario within 20 or 30 seconds. Gearmos are made as original type, or they can be gold or silver. The gold and silver Gearmos let Mario know that they want a certain creature brought to them, and the Gearmo will reward him with a Power Star. Gearmos are brought to Starship Mario when Mario does a job for them in Super Mario Galaxy 2.
- Garbage Gearmo: He takes care of the Battlerock's/Dreadnought's Ammunition Depot in the Battlerock/Dreadnought Galaxy and serves as a host to the Bob-omb Blasting mini-game.
- Gold Gearmo: He has a softness for Goombas, and has set up his own Goomba-trap in the Boulder Bowl Galaxy.
- Silver Gearmo: He has an affection for Topmen, and has set up his on Topman-trap in the Space Storm Galaxy.
- Purple Comet Host (Battlerock Galaxy): Purple Comets are her thing, and she will reward him who grabs 100 Purple Coins.
- Purple Comet Host (Dreadnought Galaxy): He has a penchant for Purple Comets like his sister does. Completing the Purple Coin challenge really completes him. Getting no Purple Coins gets on his nerves.