Yes, they are all necessary.
There are two types of superlative: the forms with 'the' and those without. The difference between them is subtle but significant: the former denotes comparison between one entity and others, while the latter denotes comparison between one manifestation and another of the same entity.
Thus, we would say
He speaks French THE BEST of all the boys in the class.
to compare his performance with that of his peers, while we would say
He speaks French BEST when he's been drinking red wine.
to compare his performance in one situation with his own in another.
The examples above involve adverbials, but precisely the same difference applies to adjectival superlatives.