Why Mothra Could Be the Alpha Titan in Godzilla's MonsterVerse
Although not as powerful as Godzilla or Ghidorah, Mothra may actually be one of the few alpha titans in the legendary MonsterVerse. That's why.

Though not as powerful as some of the other creatures in Legendary's MonsterVerse, Godzilla: King of the Monsters' Mothra may secretly be an Alpha Titan. In the Godzilla and King Kong cinematic universe, it's widely believed that the Alpha Titan is an all-powerful creature capable of commanding the respect of other monsters on Earth. But of course, only one can be an alpha of the MonsterVerse at a time.
Now, that honor belongs to Godzilla. He received this honor when he defeated the previous King Alpha Ghidorah at the end of King of the Monsters. In doing so, he managed to secure some of the MonsterVerse's tiny titans as his minions. But while Rodan and the others were quick to accept him, one monster in particular - King Kong - didn't show the same respect for Godzilla. As Godzilla vs. Kong points out, the Lord of Skull Island is Godzilla's antagonist, Alpha, who was considered a contender for the crown until defeated at the end of the film.
King of the Monsters Hinted At Mothra's Alpha Status

A detail in King of the Monsters suggests that Mothra itself may be the Alpha Titan. based on what has been So far, alphas usually don't succumb to other alphas without a fight like Behemoth and monsters do when Ghidorah fails. This explains why King Kong rejected Ghidorah's call in the novel Godzilla: King of the Monsters. Unlike King Kong, Mothra resists Alpha's call and even steps forward at the end of the film. Granted, this could be attributed to her benevolent nature, but it could also be a sign of her alpha status.
Notably, the film refers to Mothra as the Monster Queen, which further indicates her role in the MonsterVerse. But the title seems to represent more than just her regal good looks. It also hints at her unique and exalted status relative to other Titans on Earth. In the movie, there really is a sense that Mothra - who really fits the definition of an alpha - doesn't answer to anyone. She fights alongside Godzilla as he defends the balance of nature, but there's no indication she actually obeys him.
Why Mothra Would Never Become The Alpha Of The MonsterVerse

Even if Mothra was an alpha titan, she is unlikely Always seek to gain dominion over others. While she can be intimidating in combat, she's much weaker than other alphas, and doesn't seem to have enough raw power to control a titan in the MonsterVerse. Not only that, but it's hard to imagine she actually wants to be an alpha. Monsters like Godzilla seek to become the dominant force in the MonsterVerse, while Mothra has a reputation as a peaceful titan, fighting when the Earth needs her.