From Screen Rant
With Godzilla and Rodan, Godzilla vs. Kong can introduce to the MonsterVerse Toho's most iconic giant monster team-up. A role for Rodan in the next MonsterVerse installment hasn't been confirmed, but is certainly possible, thanks to the ending of Godzilla: King of the Monsters.
Godzilla: King of the Monsters added three additional Toho kaiju to Legendary's MonsterVerse: King Ghidorah, Rodan, and Mothra. Rodan is a Pteranadon-like creature who lives in a volcano and flies at destructive, supersonic speeds. Rodan, who is one of Toho's most popular monsters, has appeared in numerous live-action films - starting with his own solo film, Rodan, in 1955. Rodan also played prominent roles in some of Toho's Godzilla movies from the 1960s, and more. Over the years, Rodan has clashed with Godzilla, King Ghidorah, and Mechagodzilla.
Godzilla: King of the Monsters reimagined Rodan for the MonsterVerse with a fiery upgrade and an update to his design to make him look more imposing. In the movie, Rodan was introduced as Titanus Rodan, one of the 17 Titans hidden in the MonsterVerse. After being awakened by the Orca, Rodan emerged as a dangerous force who acted as a minion of Ghidorah. Godzilla vs. Kong, however, could take Rodan in a different direction by accurately adapting his relationship with Godzilla from the Toho movies.
Godzilla has fought alongside multiple kaiju in Toho's movies, including Rodan, Mothra, Anguirus, King Caesar, and Jet Jaguar. Out of all of them, Rodan is Godzilla's most important ally. Godzilla and Anguirus were a duo only one time in Godzilla vs. Gigan, and prior to King of the Monsters, the only time where Mothra was Godzilla's main ally was in 2004's Godzilla: Final Wars. Rodan, on the other hand, is Godzilla's most reliable partner in combat. Godzilla and Rodan were portrayed as a powerful duo in Ghidorah, The Three-Headed Monster and The Invasion of Astro-Monster.