Here's a little more info about them taken from their Wiki page:
The Quintessons are a bizarre and ancient race of mechanoids, whose origins are unknown and their history and crafty actions are bound up with the history of the Transformers, and connections with Primus and Unicron. They prefer subterfuge, scheming, and advanced technology over brute force, but if those don't work, they can fall back on the legion of deadly Sharkticons and Allicons at their command and a fleet of battle-ready spaceships as well. However, the Quintessons themselves have zero fighting abilities and are absolute cowards if they have nothing to hide behind.
The most famous of the Quintesson are the Judges. I seem to remember an episode where Ultra Magnus and a few other Autobots were captured by them. Check out a video here about them.
I'd like to see some actual toy lines of these guys but none were ever officially produced by Hasbro. Believe me, there are knockoffs that you can find on Ebay but I'd like some actual figures of these guys that are legit. You can read more about these guy here a the Autobots wiki page and see just how interesting they were. Hopefully, in Transformers 5 (which you know is coming) they'll be part of that movie and we'll be able to see Mark Walburg beating up some floating head robots. - Kevshiro