Question: is natsu stronger than god serena?
Answer: The answer is yes, however he could do that only with a PU mode (like Fire Dragon King Mode or Dragon Force), I mean, God Serena defeat 4 of the 5 (also Makarov stated that he had no chance against God Serena), maybe Natsu is not as strong as God Serena in Base Form, but his transformations grants him so much power ...