Ghidorah's alien origins in Godzilla: King of the Monsters proves that Godzilla didn't just become the "King of the Monsters" in the movie - the crown had always belonged to him as the most powerful Titan. As an outsider, fallen from outer space, King Ghidorah never had a legitimate claim to the title.
Directed by Mike Dougherty, Legendary Pictures' Godzilla: King of the Monsters throws together four giant monsters for an epic battle to determine the fate of the world. Jonah (Charles Dance), the leader of a group of eco-terrorists, engineers a plan to gradually wake up the 17 Titans on Earth. After stealing a device called the Orca, Jonah is able to awaken King Ghidorah, which results in a dramatic struggle between Godzilla and Ghidorah. Rodan and Mothra, two more classic Toho monsters, are also thrown into the mix.
In King of the Monsters, Dr. Serizawa (Ken Watanabe) believed that Godzilla would bring balance to the rest of the world by controlling the other Titans. As the apex predator, it made sense for Godzilla to be above them all. In 2014's Godzilla, it was stated that Godzilla is situated at the very top of the food chain. As the alpha, Godzilla can also command the other Titans, but a plot twist in King of the Monsters revealed that Godzilla isn't the only monster capable of such dominance.
After King Ghidorah is woken up by Jonah, the three-headed dragon manages to unleash all of the other Titans at once. After defeating Rodan, the other Titans bend to Ghidorah's will and accept him as the alpha. Ghidorah's actions, of course, threw a wrench in Emma (Vera Farmiga) and Jonah's plans. They believed that waking up the Titans would save the world, but Ghidorah, who isn't native to the Earth, turned out to be a force of destruction and chaos.
Godzilla sets things right when he battles Ghidorah for the third time in the movie and destroys him while in his burning form. Following his victory, Rodan and the other Titans respond by bowing in respect to Godzilla, which effectively crowns him as the new King of the Monsters.
However, the fact of the matter is that King Ghidorah was a pretender in a sense. Like his Toho counterpart, he was an alien invader who came to Earth. This means that Ghidorah was not part of the natural order. After awakening, he had an unusual effect on the planet's creatures. While Ghidorah may have been the supreme being of his own planet, as one character in the movie puts it, "This is Godzilla's world". This explains why Ghidorah is referred to as "The False King". Godzilla, on the other hand, is the natural alpha predator and Earth's one-and-only true King of the Monsters.