And My favorite stylization, The Warrior drone.

If you're beast enough to fly circles around Sinistar then these guys are the only problem you really have to worry about.
Quick and agile, the warriors fly in groups that will chase you for as long as you're still in one piece.
The tank like turret on top has a machine gun-like laser emitter that they are able to fire pretty damn accurately.
They can also be seen helping out the Worker Drones, shooting planetoids to release the sinicrystals they contain. They aren't much of a threat alone, but if they group, like they usually do, they can become very troublesome as they use their heavy armor to bash you into planetoids or even into the Sinistar itself.

Sinistar characters and concepts © Williams at MIDWAY
Art © tanookicatoon