The tagline on the poster proclaims:
...which means something like "Severely-wounded Godzilla's deadly Ultra C!"
Jisho.org defines Ultra C: "noun. amazing feat; trump card; (something) earth-shattering. Colloquialism, Wasei, word made in Japan, From English “ultra C”. Wasei (word made in Japan), from C having been the highest degree of difficulty in artistic gymnastics when the term was coined."
According to August Ragone, "At the 1964 Tokyo Summer Olympics, Yukio Endo had captured three gold medals and one silver with his lightning-fast parallel-bar maneuver called the "Ultra C." The term became a household word due to its frequent use by NHK announcer Bunya Suzuki, who shouted "ULTRA!" every time the Japanese gymnast scored high marks. "Ultra" became quite the catch-word in Japan." Wikipedia gives a slightly different history, tying it to the 1968 Olympics instead.
"Ultra C" was the inspiration for the title Ultra Q
. What is Godzilla's deadly Ultra C?