K0-5D began function as a general purpose ASP droid, but it has been extensively modified for gladiatorial combat. Fighting aboard the sparring pits of the Weequay pirate ship Marauder, K0-5D usually emerges triumphant, thanks to its powerful, steel-shredding servos and his integrated flame thrower. For his fighting prowess, the Weequays have taken to calling it "Maximo."
A series of misadventures during the Clone Wars resulted in C-3PO and R2-D2 being captured by Weequay pirates, and sent to the gladiator pit to fight for their mechanical lives. Though R2-D2 is crafty and equipped with all manner of helpful tools, he would not have stood much of a chance facing off against Maximo.
Although a protocol droid with over thirty secondary functions, C-3PO is not programmed for wanton destruction. He watched helplessly as K0-5D tore through an opponent, and was next in line to battle the warrior until saved by, of all beings, General Grievous.
K0-5D's destructive rampage was cut short by General Grievous. The Separatist commander used the Weequay Marauder craft for target practice. Grievous' massive Separatist dreadnought blasted the Marauder apart, and K0-5D was blown into space.