Board Thread:Questions and Answers/@comment-116.65.70.72-20130703120359/@comment-122.132.188.148-20130726111532

It could be that Ultraman has gotten weaker due to spending to much of his energy fighting other monsters without being able to heal himself much like Ultraseven and couldn`t muster enough power to defeat Zetton.

After all Ultraman`s specium ray seems to have gotten weaker over the course of his series.

He couldn`t destroy Mefilas, Skydon, Geronimon, Kiyla, and Zetton by himself.

Also he lost one against Gomora despite it not having any special powers besides super strength and also being a earth monster.