I'm gonna deliver some musings and words of stuff from the MythoRealms (comic universe).

Giants and Kaiju exist, they're about as large as a skyscraper, some as massive as mountains. But the bottom line is that they're larger than the average species. Their sizes could be caused by radiation, atomic/nuclear energy (assuming it doesn't kill them first), magic, or genetic abnormalities and/or augmentations.

I had a concept about giants considered too dangerous to continue to be giants. If they do nothing but destroy stuff and cause harm to the normal sized people, they'll be put through a process to make them not as dangerous anymore. By shrinking them to the size of an average person or member of their species. Once shrunk, they can never be giants or kaiju again. They'll even be put onto a list of shrunken giants on a registry like criminals or s*x offenders. (Being shrunken is not the same as being a s*x offender you'd have to go onto two different lists for that, one for being shrunken and so on. At least being shrunken, you can start over and recover from it somewhat.)

Assuming a shrunken giant decided to have offspring, with a normal sized person or otherwise. They'd be either born normal sized or grow to be half-giant. Kinda like Hagrid from Harry Potter.

Say Godzilla exists in the MythoRealms and he gets successfully shrunken down, he'd still be dangerous to be around with the atomic breath and his strength. But he'd be nowhere near as bad as he would be if he were still huge. He'll still retain his nuclear breath and other characteristics, but he'll only be able to use a fraction of it because of his smaller size. Therefore, rendering him not as dangerous.

What if a giant or kaiju were falsely accused of a crime they didn't do and end up getting shrunken before proof of their innocence were presented? The company who shrunk them would be very sorry and unable to return them to their previous size as the shrinking process is only one way. Unless we have Pym Particle tech, there's just no way we can return them to their normal size. But they'll compensate by paying them and giving them benefits and housing as a way of saying sorry for shrinking you.

Come to think of it, Clifford the Big Red Dog if shrunken to a normal sized dog would be okay. But if Emily stops loving him, he'd shrink to about the size of an ant. Good luck not accidentally crushing him. The rest of his life would pretty much hinge on him being loved always. But at least no more buying thousands of dollars' worth of dog food every week or otherwise. How do they get the money to not only support themselves but also a kaiju-sized dog on top of that.

Assuming kaiju and giants have a population and reproduce, how would there be enough room for all of them? My idea is that a wizard, god, or entity capable of bending reality created a realm within Earth for most of the kaiju and giant population to live in. Some would stay in the main mortal realm on Earth, but the vast majority would go to this giant realm where everything is massive to compensate for their large sizes.

Would Kaiju/Giant wrestling exist? I don't see why not, giant monsters and kaiju go at each other's throats time and time again since probably the beginning of time. Survival of the fittest.

I have a list of Kaiju/Giant Monsters to work with. I got the list from scrolling through Reddit's Public Domain subreddit. There's one guy who posts clay sculptures of dinosaurs and giant monsters with the expressed purpose of releasing them into the public domain. MagazineExpert3098 of Reddit makes them, and he's been such a great help for filling up my list of public domain characters to work with.

https://www.reddit.com/user/MagazineExpert3098/

I feel like I got everything inside of my head out. So, I'm gonna cut the post here. In conclusion, Godzilla would beat King Kong, he has atomic breath and a tough hide. With him, it's practically an open and shut case!