Did Filmation ever have a Godzilla deal?
I ask, because I just watched the animated Star Trek episode "Yesteryear", and was surprised to hear that the monster in the Vulcan desert sounded exactly like Godzilla. Not "close." Exactly. As in, somebody flat out swiped the audio clip. Unless, you know, Filmation had the rights somehow.
I'm inclined to think there must be a legit explanation. The Big G was popular enough in the early '70's for me to see Megalon and Smog Monster on the big screen in my hometown. So it's not like nobody would have noticed.
Perhaps the studio used the sound library of the party that did the English language versions of the films.
A Godzilla cartoon produced by Hanna-Barbera appeared in 1978-79.
A forgotten DC feature: "Spaceman at Work".