Ranking each Toho Monsters Based on Their Chances of Showing Up in the MonsterVerse (Very Likely to Zero)

Megalon would fit perfectly into the MonsterVerse, his original origin of being an ancient creature that was worshiped as a god by an ancient underground civilization would easily fit with the idea of the Hollow Earth and mythology of the series. Unfortunately, I don't think he's well known or popular enough to be on Legendary's radar.

Gigan seems like the most obvious choice to appear in a potential future installment due to the fact that the series has already established the idea of alien titans, that and GvK made a few references to alien conspiracy theories which makes me think they may be setting up the idea of more aliens in the series. Seeing an updated version of his design would be awesome.

Anguirus could possibly show up, King of the Monsters made a few references to him with a skeleton being located outside of Godzilla's lair and a moment where you can actually hear his roar. Concept art for the unused monster, Rokmutul, also took heavy inspiration from Anguirus, so we know that he's definitely on Legendary's radar.

Destroyah makes sense as a future villain, due to the Oxygen Destroyer being used in KOTM, and while he isn't too well known to the general public, I think audiences would have no trouble embracing his design.

Hedorah, would be a great addition, an updated version that emphasizes how creepy and disgusting it is could work really well.

Titanosaurus NEEDS to return to the series (and no, "Godzilla Aquatalis" doesn't count!)

Biollante would be an interesting choice for the series. Since a lot of creature movies have a focus on genetic engineering, Biollante could be a good way of introducing that idea of biological man-made titans.

Orga is one of the more unique aliens in the series so it would be cool to see him full return to the series (No, the 2 second "still image" cameo in Planet of the Monsters doesn't count as a "full return")

Giant bugs like Kumonga and Kamacarus probably wouldn't show up due to the fact that they aren't really unique designs and the MonsterVerse already has a lot of giant bugs (specifically spider-like ones), so it wouldn't be worth buying the rights to use them.

It wouldn't be worth getting the rights to use Gorosaurus either, considering that his design is a pretty basic outdated theropod dinosaur, the only thing that's really unique about him is his "kangaroo kick". The fact that a recent Coca Cola ad featured a dinosaur that looked nearly identical to him and Toho seemed to have no problem with it is pretty telling.

Not going to lie, I think it would be kind of funny if we actually saw Zilla show up (maybe as a relative to Godzilla's species), it would be interesting to see the old "American Godzilla" in the series with the new one.

@SasquaDash: 

What you said about Gorosaurus, Kumonga, and Kamacarus can also apply to Titanosaurus. There’s no point in Legendary paying Toho millions of dollars just to license an aquatic dinosaur when they could pay concept artists to design one on their own. In fact, the MonsterVerse has already introduced an aquatic Titan named Tiamat, who made her first appearance in Godzilla: Dominion. If Legendary wanted Godzilla to fight an aquatic monster, they could just have him fight Tiamat again instead of going the extra mile and getting the rights to a monster that fills the same role. 

In fact, most of the monsters from the Showa Era, with the exception of Gigan, Hedorah, Jet Jaguar, Anguirus, and Megalon, don’t really need to be licensed for the MonsterVerse. Like, there’s no reason for Legendary to pay Toho for the rights to King Caesar when Sekhmet, one of the Titans awoken by Ghidorah, is said to resemble a sphinx or lioness. There’s no need for them to get the rights to Manda since Tiamat is a sea serpent, and there’s certainly no need for them to invest money into buying Ebirah since it’s so easy to create a giant lobster here in the United States. Look up all the unused designs for the MUTOs and Scylla, and you’ll that the people working on these films already have the skill set to design crustacean-like Titans for future films. 

What I think a lot of fans fail to realize is that Legendary can’t just purchase more Toho monsters just for the sake of doing it. Unlike Marvel and DC, they don’t own all these IPs. So before they think of purchasing a specific monster from Toho, they really got to sit down and determine whether purchasing this IP would be worth the investment or not. I bet they’d want to be very selective on who they decide to spend their money on. 

Jack Capellini

I would argue that Titanosaurus is a bit more unique than Ebirah, Kumonga and Gorosaurus, due to him being a mix of dinosaurs, fish, and other marine creatures, whereas the others are just oversized animals.

I do agree that if Legendary are going to buy the rights to use older Toho monsters, they'll probably go for the crazier, more unique, and possibly more well known ones like Gigan, Biollante or Destoroyah. 

Oh I see. If that’s the case, than there might be a better chance of Titanosaurus showing up, though I still think it’s very low.

The only way I could see these Showa Era monsters showing up would be in the form of easter eggs. Let’s say that in the next movie, Kong travels through the Hollow Earth trying to assert his dominance over all the native Titans, and one of the locations he travels through is an ancient battlefield filled with the remains of Kong’s ancestors (like in the Temple with the axe). One set of remains is a Kong with its hands prying open the jaws of a giant tyrannosaur. The tyrannosaur could serve as a nod to Gorosaurus. This wouldn’t be very far fetched, as we saw Anguirus’s remains next to Godzilla’s temple before it got destroyed in KOTM. There was also this giant Triceratops skull in the boneyard on Skull Island, and it wouldn’t be out of the realm of possibility that dinosaurs also lived in the Hollow Earth. 

If Legendary ever decided to include Gorosaurus along with other “lesser” Toho monsters, I bet they’d simply slip them into a film without having to actually use them if you know what I mean.