NTSE aspirants from States which follow CBSE curriculum in NTSE Stage I definitely have advantage over others. If the cut off of their State in NTSE Stage I is also high (above 130), they can easily make it to top 1000 students in NTSE Stage II.
Students who have studied class IX and X from State board will face problem as syllabus of NTSE Stage II is from NCERT. Same way students from States which follow State board syllabus for NTSE Stage I will also face problem, because had to study State syllabus for NTSE Stage I and now will have to concentrate on NCERT syllabus.
Previous results show that students from Delhi, Rajasthan and Chandigarh have easily made it to the top 1000 students in NTSE Stage II, reason - syllabus for NTSE Stage I and II both are from NCERT and cut off in Stage I in these areas were also very high. (Cut off for Delhi this year for General Category was 133, Rajasthan - 137 and in Chandigarh was 142).
Last year maximum students who made it to be NTSE Scholars were from Rajasthan (130 selections), followed by Maharashtra (103) and UP (86).
If we go by % of selections - Chandigarh was on the top (8 became NTSE Scholar out of 13 students who cleared NTSE Stage I - 61.54% success rate), Delhi 49 of 86 (56.98%), Rajasthan 130 of 274 (47.45%). Other than these Haryana 39.22%, Odisha 34.38%, Punjab 33.33% were the major contributors