Sentence examples for he fights from inspiring English sources

'he fights' is a perfectly correct and usable part of a sentence in written English.
You can use it any time you want to describe someone who is engaging in physical combat or an altercation. For example, "Rudy had trained for months to prepare for his championship boxing match, but despite all of his hard work, he found himself losing the fight. He had no choice but to grit his teeth and keep fighting."