None.

Monsters destroy a city

A shootout. Blood is seen when one man is shot in the stomach and another is shot in the head.

A man commits suicide by jumping out a window. We later see him undergoing his autopsy, and in a brief shot, we're shown the scalpel penetrating his flesh, revealing some blood. Japanese and English versions cut away quickly thereafter but return to show the surgeon remove an alien control device (a small sphere) from the incision.

Earings are ripped off a woman's ear. Some blood drips from her one ear.

When the monsters battle King Ghidorah, he gets a little bloody.

Very little.

Some smoking.

Nothing too frightening.