@AggressiveKaiju45
He doesn't transform into his Burning form. He was mutated into it by accident. He appears in that form at the beginning of the film and his condition worsens throughout.
A radioactive fissure erupts on Bass Island, where he and Little Godzilla were staying, and it overloaded his heart which is equal to a nuclear reactor. It caused nuclear fission in Godzilla's body that would force him to explode and take the planet with him.
Later in the movie G-Force gets the fission under control, but the heat within Godzilla's heart continued to rise. So instead of an explosion, if his heart [reactor] melts, so does he. His meltdown was initially supposed to destroy the world as well, but G-Force found away to freeze him while he melted in order to minimize the damage. Only Tokyo is left feeling the effects of his death.
Burning Godzilla may be the most powerful form of Godzilla (arguably), but it comes at a cost. It's very far from intentional and ultimately cataclysmic.
"'Nostalgic' does not equal 'good,' and 'standards' does not equal 'elitism.'" "Being offended is inevitable. Living offended is your choice."
