Toho had planned on giving "Sukeruton Kame" or "Suke" to his friends, his own series of spin-off films.
But at this point Godzilla was becoming really popular and used his political clout to get that squashed.
You see Godzilla was very over-protective of his career and he didn't want any competition. He was the reason Toho never built a franchise around King Kong even though they still had the rights. He's the reason Mothra and Rodan only got the one solo movie each when there was more then enough of demand for a franchise for both of those Kaiju. He also used his power to squash Varan's film career. Why do you think Varan was reduced to a brief cameo in Dam? Godzilla never forgave Varan for dating his ex-girlfriend and used that to destroy his career.
So the same thing happened with "Suke". There were plans to make a whole series of films. Everything from Sukeruton Kame vs. The Smog Monster. Sukeruton Kame vs. Mecha-Sukeruton Kame. Sukeruton Kame Final Wars. Sukeruton Kame vs. The Thing from Uranus. You name it. All of these film projects were squashed and Godzilla even stole some of them for himself.
So the next time you see "Suke" remember what could have been. And you have no one but your "precious" Godzilla to blame.