Godzilla has displayed an uncanny ability to sustain damage throughout his films.
Starting in the first Godzilla film, Godzilla displayed an immunity to conventional weaponry, virtually impervious to everything the JSDF threw at him. He has demonstrated the ability to survive complete submersion in magma for an extended period of time, sometimes while under extreme pressure from tectonic plates (as seen in Godzilla vs. Mothra). He has even survived being in ground zero of asteroid impacts. The only times his flesh has been visibly pierced were in battle with the Super X, Showa Gigan, Biollante, King Ghidorah, Destoroyah, and from MechaGodzilla's weapons in the Showa, Heisei and Millennium series.
In addition to being extremely resistant to damage, Godzilla possesses an extremely advanced and highly efficient regenerative ability. This power was a crucial plot point of Godzilla vs. Biollante and Godzilla 2000: Millennium. In Godzilla 2000, it is explained that Godzilla's regenerative abilities may have something to do with his radioactive properties, and Regenerator G-1 ("Organizer G-1" in the Japanese version) is the name given to a substance in his cells that is responsible for Godzilla's swift healing. In Godzilla vs. Biollante, Japanese scientists use samples of the Godzilla cells (called G-cells throughout the Heisei series of Godzilla films) to help create the ANEB. This healing factor would be inherited by all creatures spawned from Godzilla's DNA, those being Biollante, SpaceGodzilla and Orga.