Are 12th board marks included in the nata result?
As per your query IF you are not from Maharashtra. So if you want JJ then you NATA score should be somewhat 140+ and boards % 95+. Still then your chances are rare. If you belong to any reservation category, then you can try.
NOW, If you are from Maharashtra then you will get admission to JJ with a decent NATA score, say. 100+ and a board % more than 80..
Last year 2018 cutoff;
For General Candidates:148.46
For SC Candidates: 128.69
For ST Candidates: 116.46
For SBC/OBC Candidates:150.2
All the best.