Sludge

The hapless Sludge is a member of the Lightning Strike Coalition, serving under the command of Grimlock.

Fiction
Shortly before the Great Exodus, Sludge was a member of the Lightning Strike Coalition, a brutal subgroup of Autobots under the leadership of Grimlock, who reluctantly followed Optimus Prime's more cautious brand of warfare... when ordered. Swoop was sent to investigate Shockwave's energon sources but he worryingly disappeared. When the other four coalition members learned that Swoop had been captured by Shockwave, they disobeyed orders and went after him themselves. Good Intentions Sludge and the others followed Grimlock, secure in his arrogance, who was glad that the fate of Cybertron rested in their hands. Secrets Although the group attempted to rescue Swoop from Shockwave's experiments, they were overwhelmed by Insecticons.

Rage of the Dinobots
Sludge was among the Dinobots, alive and well somehow. He helped the last convoy of ships led by Impactor escape Cybertron. Ultra Magnus told the Dinobots to get to their own craft, but another squadron of Decepticons drew Swoop into taking them out himself. This resulted in Magnus being shot down when he tried to fend them off. Grimlock convinced the other Dinobots to attempt a rescue for Magnus. A Predacon, however, managed to get there first and capture him. Swoop was downed and captured in the process.

Sludge examined the bodies of the Predacons that were destroyed while trying to capture Ultra Magnus. He let Grimlock know that there were welding lines that indicated the warriors were cut up and sewn back together again, just as Shockwave did to the Dinobots. Snarl got Ultra Magnus' ship up and running and they followed Swoop's transmitter.

The Dinobots found the prison atop a mountain. Once they arrived at the top, the Dinobots took out the guards and Snarl was able to steal a module from one of them. The Dinobots found that the prison contained far more prisoners than they were expecting. The Dinobots managed to open every cell, but had to manually release Magnus. When they returned to the top, they met eyes with Ser-Ket. The Dinobots demanded that she hand over Swoop, but she revealed that Swoop had been re-forged into a Predacon.