User blog comment:Drakan95/BoJack Horseman vs Mr. Ed. Epic Rap Battles: Cartoons vs History. Season 1.5 Premiere/@comment-5101200-20150818190239

Zim vs ET.

Aliens that came to Earth, one with neutral/non-hostile intentions, the other to invade, and both are somewhat known for disguises (ET on Halloween, Zim with all of his weird ones).