The Rhynocs served as the Sorceress's main attack force, acting on her orders to terrorize the Forgotten Realms and enforce her rule. When Spyro came to reclaim the stolen Dragon Eggs, the Rhynocs were dispatched to dispose of him, with Bianca referring to them as their "expertly trained armies" when she tried to scare Spyro off. They are hostile enemies to Spyro in the majority of the realms within the Forgotten Worlds, with few of them being turned into monsters by Bianca and the Sorceress in attempts to destroy Spyro, only to end up destroyed themselves.
Spyro: Season of Ice
After the Sorceress's defeat, the Rhynocs discovered that they had no sole purpose, even when they served her. Many of them were left jobless or had to take less-than-ideal day jobs. They were soon employed by a large, manacial Rhynoc named Grendor, who then sent them to gather for him the 100 fairies he had frozen to give him more power and to fight off Spyro.
Spyro 2: Season of Flame and Spyro: Attack of the Rhynocs
After Grendor's defeat (and reformation), the Rhynocs once again felt unneeded and useless, until they were employed by Ripto. Ripto controlled the Rhynocs when not using his army of Riptocs during the events of the Season of Flame, and after stealing the Professor's Laboratory in Attack of the Rhynocs. Rhynocs have not been seen since.