Created by Dr. Light and Dr. Wily to be an all around support unit, Rush has the ability to transform into at least two different forms; Rush Marine and Rush Jet. As Rush Marine, Rush becomes a small, one-seated submarine while Rush Jet transforms his legs into jet engines that let him take flight. Rush also has the Rush Coil, which is a spring that pops out of his back and helps Mega Man reach higher platforms that he normally couldn't.
In later games, he can attach himself to Mega Man and make a Jet Adapter, which lets Mega Man perform a double jump, a Power Adapter, which lets Mega Man fire a very strong Mega Buster blast, and a Super Adapter, which is a somewhat fusion of the previous two, allowing Mega Man to double jump as well as launch his arm like a projectile (similar to the "Mega Arm" of Mega Man V).
Rush Cycle, where Rush transforms into a motorcyle for his master to ride, appeared in Mega Man 8.
Rush appears in the latest installment of the series, Mega Man 10.