Hii Riyas 

NATA is a national level entrance test conducted by COA(Councill of Architecture) every year to get admission into B.Arch courses 

For getting into good B.Arch Universities candidate must score ;

40% mark in Nata exam or 80 marks from 200 marks.

If you wants to come under merit your percentile should be 70+ such that you can easily enters in elite institutes.

Coming to board exam percentage it should be more than 80% such that you have ample of opportunities for entering into good colleges.

All the best