All three of the major Titans that were introduced in Godzilla: King of the Monsters - Rodan, Mothra, and King Ghidorah - can return in Godzilla vs. Kong. Along with Godzilla himself, the three Titans were at the center of the action in the last MonsterVerse installment. Like Godzilla, all three are properties of Toho, who has made several movies with them over the years. In order to use them for King of the Monsters, Legendary had to acquire the rights from Toho.
After being teased by a cave painting in a post-credits scene featured in Kong: Skull Island, the trio of Titans officially made their MonsterVerse debut in Godzilla: King of the Monsters, with two of the three playing their traditional roles. As expected, Ghidorah was the villain, and Mothra was a benevolent monster and an ally to humanity. Rodan, on the other hand, fought on the side of King Ghidorah after losing his own battle with the three-headed dragon. Ghidorah, who turned out to be an alien invader - just like his Toho counterpart - woke up the MonsterVerse's original Titans and became their new alpha. It was up to Godzilla to stop Ghidorah and put an end to his reign.
In the end, only two of the four Titans were left standing. A two-on-two final showdown with Godzilla and Mothra taking on Ghidorah and Rodan ended with the deaths of Ghidorah and Mothra. After Ghidorah was defeated, Godzilla found himself surrounded by Rodan, Behemoth, Scylla, the third M.U.T.O., and Methuselah, who all accepted him as the new King of the Monsters - the Earth's Alpha predator. The next challenge for Godzilla to face is, of course, Kong, but it's possible that the upcoming fourth installment in the MonsterVerse can bring back Ghidorah, Rodan, and Mothra into the story. Here's how it could work.
Mothra
Similar to what Rodan did in Godzilla vs. Mechagodzilla II, Mothra gave what remained of her life force to Godzilla, so that he would have the strength he needed to defeat Ghidorah; her death made Godzilla's victory possible. Mothra's demise was a great loss for the MonsterVerse, but as King of the Monsters director Mike Dougherty has said in the past, "Mothra never really dies". Mothra goes through a cycle that sees the character transform, lay an egg, die, and be reborn again. Also, the newspaper articles in King of the Monsters' credits sequence did reveal that Mothra laid an egg prior to her death, so the pathway to rebirth has already been created. Being killed by Ghidorah isn't the end for Mothra, but what isn't clear is if her story will ever be continued in the MonsterVerse.
She could possibly return in Godzilla vs. Kong when it comes out in November 2020. It could be that there are plans for Mothra to made an immediate return, based on the casting of Zhang Ziyi, who played Dr. Chen in King of the Monsters, and for a brief scene, her twin sister, Ling. It was revealed in the movie that Dr. Chen and her sister are the latest generation in a long line of twin sisters who have worked for Monarch. As it turns out, the two represent the Twin Fairies from the classic Toho movies. In Toho's Godzilla and Mothra movies, the Twin Fairies communicate directly with Mothra and share a strong bond with the character. Through Zhang Ziyi's characters, the MonsterVerse has their own version of them, and Mothra was expecting to see when she first emerged. King of the Monsters never had much of a chance to explore this connection on a deeper level, but with Zhang Ziyi reprising at least one of her roles in Godzilla vs. Kong, this could be expanded on in the movie. This time, Dr. Chen could be present when Mothra is reborn.
King Ghidorah
King Ghidorah, who battled Godzilla (and lost) thousands of years ago, met his end at the hands of Godzilla in King of the Monsters. After having his body obliterated by one of Burning Godzilla's nuclear pulses, Ghidorah's final head was eviscerated by the kaiju's atomic breath. Godzilla made sure Ghidorah stayed dead, but could a way still exist for him to come back? During their second fight off the coast of Mexico, Godzilla severed one of Ghidorah's heads, which appeared to be lost at sea. But in Godzilla: King of the Monsters' post-credits scene, Jonah (Charles Dance) came into possession of the head, though what he has planned for it remains a secret. It could be that his intentions for it involve Ghidorah's regenerative qualities. If so, Ghidorah's head could be used to create an entirely new Titan. Alternatively, it could be how Ghidorah returns to the MonsterVerse.
The King of the Monsters credits have revealed that Monarch is capable of creating organic Titans and also possess the technology needed for making a "mechanical giant". If Jonah and his people can somehow get their hands on these resources, the MonsterVerse can restore Ghidorah in the same way that he was revived in the 1991 Toho film, Godzilla vs. King Ghidorah. In the movie, Godzilla killed Ghidorah, only for him to be rebuilt with a metal head. His new form was given the name "Mecha-King Ghidorah". If the MonsterVerse had its own Mecha-King Ghidorah, it could be an ally for Mechagodzilla, Nozuki, or both. Since Godzilla vs. Kong may need multiple villains, this could possibly work for the movie's story. Instead of focusing on one antagonist, Godzilla vs. Kong can see the two titular Titans battling two or even three enemies.
Rodan
Rodan survived the events of King of the Monsters and is now a minion of Godzilla. The credits of King of the Monsters have revealed that at some point after the fight ended, Rodan found a new volcano to take roost in. What this means is that Rodan may be back in hibernation and unavailable for whatever conflict Godzilla will have to contend with in Godzilla vs. Kong. That being said, Rodan could always be summoned by Godzilla, just like how Ghidorah awakened the fiery beast in the last movie. Rodan was on Ghidorah's side in King of the Monsters, but Godzilla vs. Kong can show a different side to the classic Toho kaiju by pairing him up with Godzilla, something that was briefly considered for the 2019 film.
In the 1960s Toho movies, Godzilla and Rodan were a dangerous duo who saved the world from King Ghidorah on two separate occasions. They're Toho's most iconic giant monster team-up, and fans were denied a chance at seeing this relationship represented in the MonsterVerse in King of the Monsters, but Godzilla vs. Kong could rectify this. It could be that when Godzilla travels to Skull Island - or perhaps a different location - he'll bring Rodan along for the ride. Having Rodan on his side would give him a powerful ally that could help him in the battles to come. Of the three, Rodan of course has the easiest path to making a second appearance in the MonsterVerse, but it's at least possible for all four of the main Titans from Godzilla: King of the Monsters to reunite in Godzilla vs. Kong.
