Sideman is the bird partner of Bluegrass.
After the creation of Sky Shadow, the SilverHawks created avian partners to assist them. These four robotic birds were called the Fighting Hawks. Sideman is one of the four Fighting Hawks, created to respond to greater threats of the Limbo Mob. He was created to specifically support Bluegrass.
Sideman is a transforming robotic hawk. In hawk mode, he can fly through a planet's atmosphere as well as through the "space" of Limbo. He can fire a blue music energy beam similar to Bluegrass's Hot Licks from his head. He can also transform into a guitar form, extending his neck, folding in wings and claws. In this form, he is most likely "programmed" with the music he uses when in combat. He can also assume a hybrid form, extending his neck to act like an antenna.
While not designed for reconnaissance, it is possible for the SilverHawks to decode his memory banks in order to find out his recent experiences. While he cannot carry much weight, he has also been shown to be able to slow Bluegrass's fall to a safe level.