We can only hope that Godzilla has perfect matter-to-energy conversion (for firing that mouth-beam of his, for example), and thus does not need to poop. :sleep
Then again, we've never seen Godzilla either eat OR poop! :eek
He only gets woken up, climbs up onto land, devastates Tokyo, and then slinks off into the sea again. Every few years. :lol
A few interesting Godzilla related books (in English) are
The Official Godzilla Compendium: A 40 Year Retrospective
An Unauthorized Guide to Godzilla Collectibles (Schiffer Book for Collectors) by Sean Linkenback
Godzilla on My Mind: Fifty Years of the King of Monsters
Of course there are many many fantastic illustrated Godzilla books... in Japanese. I have a few of these too but cannot read them. :unsure