Hi Neeraj,
If you score 200 marks in AISSEE Class 9 (out of 400), admission in Sainik School Rewa is very unlikely.
Previous years’ Class 9 cut-off for Rewa was around 335–360 marks, depending on category and state quota.
Even the expected national cut-off for Class 9 Sainik Schools is roughly 250–270+ marks.
So, 200 marks = qualified level, but not sufficient for Rewa selection.
You may still get chances only if seats remain vacant or in newer Sainik Schools during counselling.