I have a cartoon on the wall of my office, photocopied & enlarged from an old issue of STARLOG says "Fact: Mace does not work on Godzilla"
Actually, You know what I want to see?
I want a Nuclear Physicist to Apply real world Nuclear physics stuff to Godzilla & his weapons.
Back to the question..
I'm just stuck with the "Would a nuke kill Godzilla?" question.
This is a creature that survived for several years swimming around in a pool of 700 - 1300 degree lava, with no visible damage when he got out.
However, a Nuclear Blast is measured in MILLIONS of Degrees, not hundreds.
Question 1.
Would his armored hide and rapid healing ability prevent him from being Vaporized by the heat wave and scattered by the blast wave?
Question 2.
How much would there have to be left of G for him to Regenerate if he wasn't completely vaporized??
Then we have the problem of which is worse? A - Godzilla and his after effects or B - A nuclear detonation & it's after effects?
And the Biggie.. Would Nuking a living, breathing nuclear Reactor be far, far worse than just letting the creature be?
Who knows what sort of chain reaction that could cause..
As far as chemical or biological weapons..
Well, a Bioweapon engineered to work on him might not have any effect on other life forms, same with a Chemical weapon.
On the other hand.. they Might.
I like the Monsterland approach best.
Lure him to a comfy island, Feed him and try to keep him from wandering overmuch.