Another alternative is: "He is good tempered."

Yes you can. When people speak they would typically say "he's got a good temper". If you are writing this I would go with "he has a good temper".

"He has an affable temperament", "he's genial", "he's good natured", "he's equable", "he's good/even tempered". "he has a pleasant/agreeable disposition"

It is but you can also say "his temper is good" 😊