I notice that you're looking for multiple seasons for same ID
I.e. If ID has both Season16 and Season 15 then Flag is 0 else 1.
Since row with id = 3 has both records as "Season 15", you want the flag to be "1"
Slight modification to Phil's answer. Including "distinct" on the count would be required.
SELECT t.Id
, Flag = IIF(COUNT( distinct value) > 1, 0, 1)
FROM #test t
GROUP BY t.Id;