Hi,
He is (very) good -- Obviously this is a good sentence.
He is (very???) better -- Usually, we would use the word like "far" to increase the amplitude.
He is the very best -- Yes, I think this is OK, if you want to amplify the effect like this, you will need more context or a phrase (or a clause) that would qualify the use of the adverb "very."
beautiful -- more beautiful -- the most beautiful
terrible -- more terrible -- the most terrible