WordNet records no synonym and no antonym for weekend warrior. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a homeowner who acts as a contractor and tries to do major improvement projects on weekends (often without understanding the scope of the work to be done)
a reservist who fulfills the military obligation on weekends
Synonyms, antonyms and the broader and narrower relations for weekend warrior come from Princeton University’s WordNet. Full sources and licences.