Hmmmmmm,

It would have to be a group of pure evil who leave nothing but destruction in their wake...

In no particular order... G1 Sixshot, G1 Bludgeon, G1 Overlord, Car Robots Scourge, WW The Fallen & as their leader - G1 Black Zarak
(I'd also include G1 Unicron in this group if it weren't for a silly Matrix showing up unexpectedly... )