Well I suppose this can be heavily debated. Theres many irregular pieces of evidence that seem to support both sides of the debate with
whether Godzilla is a herbivore or indeed a carnivore.
Gojira 1954:
Godzilla was originally going to prey on cattle on the Odo island.
In fact that famous scene where we see him rising from behind the
hill was originally supposed to show Godzilla chomping on a cow hanging
out of his mouth.
But likewise Honda or maybe Tsuburaya thought it was too violent so
they cut out that scene
Son of Godzilla:
Minya is fed fruit by the native girl on the island.
Godzilla vs. Biollante:
Godzilla used his fangs on several occassions to bite into Biollante's
vines in a beastily fashion. That alone should show that he has
the animalistic characteristics of a carnivore.
Godzilla vs. Mothra:
-Godzilla uses his fangs to bite into and kill Battra while the he's being
airlifted via moth power. Same use of fangs and teeth as in Biollante.
Godzilla vs. Mechagodzilla II:
-Baby Godzilla is seen eating a rose stem and all. A sign of the Godzillasaurus species as herbivore? Who can tell?
Godzilla vs. Destroyah:
Godzilla Junior apparently kills several whales that later show up as dead
mangled corpses on the beaches of japan
Godzilla 2000:
Godzilla uses his teeth several times to bite Orga on his hand and such.
Godzilla, Mothra, King Ghidorah: (GMK)
-Godzilla clearly uses his teeth on several occassions to bite the living hell out of King Ghidorah. Leaving blood to trickle out of Ghidorah and onto and between Godzilla's teeth.
Godzilla tokyo sos:
Godzilla takes a large bite out of Kamebas (death blow to the neck)
So the virdict? Well it seems that throughout history Godzilla has been shown to use his teeth and biting power many times on screen. Sometimes even killing his opponent. While his godzillasaurus incarnations, rather specifically the baby incarnations such as baby godzilla and minya seem to be herbivores.
I guess only young godzillasaruses are herbivores. While the full grown mutated Godzilla is a carnviore.
