IDW comics
Flak was one of the many Dead Universe Micromasters that pursued Hardhead and Nightbeat on the planet, Gorlam Prime.
Marvel comics
Flak and the Battle Patrol were ordered to investigate the Decepticons secret weapon that was in developement. Upon breaking into the secure Decepticon base a they walked right into a guard. Flak certainly did not take kindly to having his lack of hight pointed out to him and promptly blasted a hole in the Decepticons chest. The whole mission was a trap however and the Battle Patrol was captured and were dissected with their Micromaster technology reverse-engineered. The Battle Patrol was later rescued by Roadhandler and other Autobot Micromasters, but it was to late, the Decepticons had learned the secret of the Micromasters.