Hello Aspirant,

  There are some colleges which only accepts jee mains paper 2 score for admission in B.arch courses like NITs, CFTIs. But other government and private colleges only consider NATA score for admission in B.arch courses. So, if you are looking for NITs and CFTIs then you do not have to appear in NATA, but if you are not confident about either you will get seat in NITs or not then it's best for you to appear in NATA. Also many colleges who are offering B.arch courses only consider NATA score so it is advisable to appear for NATA so that you have options open for yourself. 

Good Luck !!!