Complex sentence: Like Optimus Prime, in robot mode Wheeljack has a retactable faceplate that he wears in combat, which when covering his face, makes him resemble the Generation 1 Wheeljack.
Split into simpler sentences: Like Optimus Prime, in robot mode Wheeljack has a retactable faceplate that he wears in combat. When the faceplate, which when covering his face, he resemble Generation 1 Wheeljack.