Rack'n'Ruin are (is?) two Transformers who were surgically combined in a desperate attempt to save their lives. Previously, (t)he(y) turned into jets, but now (t)he(y) don't (doesn't?).
Marvel Comics continuity
Rack n' Ruin were (was a?) Wrecker(s). After doing almost nothing in Operation: Volcano, (and being the only member(s) of the team to not doubt the mission), they helped Roadbuster blow a chunk out of Galvatron in the Time Wars. However, they didn't bother warning him the gun was about to blow up in time, proving two heads don't tend to be better than one. Rack n' Ruin shot a hole in Galvatron. Galvatron got payback. Bye, bye, Rack! Bye, bye, Ruin!
- In his (their?) first appearance during Target 2006 (t)he(y) is (are?) referred to as "Rack and Ruin" but subsequent appearances pep this up to Rack'n'Ruin.