Megatron has spent millions of years commanding the Destrons (known as Decepticons in English releases) in an endless war to conquer the universe. He's best known for his ruthlessness—both toward his enemies and his own troops, whom he keeps in line through sheer intimidation and force of will.
Megatron is essentially a living weapon. He's constantly modifying his own body to boost his power and destructive output, making him increasingly formidable with each upgrade. What holds him back isn't physical—it's his obsession with universal domination. His ego and talent for manipulation are unmatched, and he's convinced that only he can rule everything.
His main rival is Galaxy Convoy (Optimus Prime) and the Cybertrons (Autobots), and their conflict drives much of Megatron's actions. He's also driven by the hunt for the lost Planet Forces, or Cyber Planet Keys, which he believes will give him the ultimate edge. Whether that obsession is a genuine weakness or just fuel for his ambitions depends on who you ask—but fans generally agree it's the one thing that might actually trip him up.
Content compiled by AnimeList.moe from publicly available sources.