If you can design a kaiju nemesis to Godzilla...

I suppose my original Kaiju, Mandogon would suffice. He was originally intended to act as an enemy to Kyorah, but...

Anyway, he is a burrowing creature who lives in the Earth's mantle until a disturbance drives him to the surface worthy of his attention. His abilities primarily include spewing focused streams of corrosive fluid, with a powerful jaw and the ability to constrict his prey with his body. He is a legendary creature, often depicted in folklore as a maintainer of the Earth, spinning threads to keep the world in one piece.

Monster Name: Noroc

Noroc would be more of a melee brawler than one with a beam or energy weapon, just because those have been exhausted imo. But it would definitely be more of a challenge than King Kong or Kamacuras.

It would be a little 'Gorilla'-ish in terms of posture, but not in frame. In that it would rest on smaller hind legs, and even 'upright' it's posture would still be leaning forward at an angle.

It's front arms would be the highlight of the creature. Each arm would be large, and feed into two broad "shield" like structures, both taller (when held perpendicular) than the monster itself. Each would be curved, like a jackal blade, coming to sharp points at one end, and a thick, broad base at the other. The two arms would be capable of fitting together into a single structure, like a yin-yang puzzle piece.

These arms would have two primary modes, a cool 'solid' state, in which case they could be used as clubs, or defensively to block attacks (even capable of withstanding Godzilla's Atomic Breath with ease)

And a 'molten' state, where the edges of the arms would heat up, glow orange, and could be used like a hot knife. In this state, the arms would have lesser defensive capabiliites, but would gain the offensive ability to cut through just about anything (including Godzilla's hide)

These broad 'shield-arms' would be the only part of the animal with these special abilities. If attacked from behind, the monster would be more vulnerable, and just have generic kaiju durability. It would also take a few seconds for the monster to switch between modes.

It's hind feet would have very bird/reptilian like talons, but more for gripping/hanging than for combat.

It would be of a medium build, not as bulky as King Kong or Destroyah, but not as nimble or needle-like as the MUTO. Think of like a middle ground between Otachi and Leatherback like Matt Damon or Mark Whalber musculature instead of the Governator or Stallone......but it would still be a muscular, imposing animal. 

It's jaws/head would be small, squat with short teeth. Not its primary weapon, but capable of a bulldog style bite in a tight pinch.

I've always envisioned this monster as primarily blue in color, with patterns ranging from navy blue to turquoise. The 'Shields' would have elaborate, thin patterns that were dull/rustic red in color around the perimeter, as well as streaking/cracking through the middle. These would be the sections that would glow bright orange in the 'molten' mode.

Tyranitar!!!!!

I spent an hour writing this stuff and my site crashed so I have to rewrite everything. (sigh) My personal invented monster that would pit against Godzilla and possibly become his archnemesis would be this:

Its name is Murmund, it is a reptilian like Kaiju, walks on fours, similar to a Komodo Dragon, that lives in the Earth's mantle, where it is basically treated like its ocean. It doesn’t have a specie, it has had a completely solitary existance since its inception. It has lived most of its life in extreme pressure and temperatures so it is a creature that very much has those qualities, its blood is made of lava-like substance, even though it isn’t actually molten rock. Its skin is completely encrusted, so there isn't any signs of cracks or hints that its insides is even lava-like, apart from its mouth and eyes which would be constantly glowing. It doesn’t appear to be affected by the cold, as abyss water levels or arctic regions makes little to no difference. It portrays deep levels of intelligence that rivals or even surpasses human qualities, using clever and complex tactics during a battle.

Its assaults are mostly volcanic in nature, its most basic attack consists of deadly fireballs which are blasted rapidly out of its mouth like projectiles with adamantium metal (an element completely unknown to science) that coats its hands. It can spew huge amount of lava quantities (But oddly never in combat), release deadly gas and pyroclastic breath, enough to cover the sky around its surroundings in minutes. If it is wounded it can easily reshape its skin however it needs and can even increase its armor thickness with its lava substance that would be coated out of its mouth. It's essentially a walking volcano, apart from its most powerful and deadly attack which is similar to a Solar Flare, where a massive collection of energy is focused in a blinding blast that would erupt from its mouth.

It's a completely mysterious creature, its origins are unknown, it does not care for the events on the Earth’s crust or even the need to surface it but if it does ever come out, it would not be anything good. By this canon, all we can discover from its background is that it is at least a billion years old and responsible for the Great Dying extinction which occurred 250 million years ago, an event that destroyed Godzilla’s race. So it’s safe to assume that its return would mean the repeat of such event, as to why it would do it again is enigmatic.

This thing is basically hell’s incarnate. I’ll be happy to hear what people thinks. I’ll be glad to expand on this.

I will call him ( Í¡° ͜ʖ Í¡°) and he will be beautiful.

Cool ideas so far. I seriously think some of the kaiju designs here will make a real good advesary for Godzilla. Keep them coming!