CBSE 10th

If you want to do B.Des, you can choose any stream arts, science and commerce. I am doing B.Des from arts stream because to mainly focus on design entrance exams from the best institutes like NID, NIFT, UCEED, etc. However, your class 12th score doesn't matter much, it's just that you have to score 50% to fulfil the criteria Although, you have to do your best in HSC to score well, it can rather help you in future, but your B.Des entrance score matters the most. You have to give your 100% over there. It is as hard as JEE CET NEET. But it's way more fun to study design. So, you can go for any stream, it's up to you.
All the best for your future.

Hello Aditya,
No, 10th or 12th class marks are not considered during admission into MIT. All you need to do is to take some tests.
1) The SAT or ACT, as well as two SAT subject tests, one in Math ( level 1or 2 ) one in Science (physics or chemistry or biology).
2) The TOEFL (MIT does not accept IELTS as well as two SAT subject tests, one in maths (level 1or 2) one in science (physics, chemistry and biology). This is especially recommended who do not speak English at home or in school, or who have been speaking English for fewer than five years.
Requirements for application:
GPA requirements
Testing requirements including SAT and ACT.
Application requirements.
To get into a college, firstly look at the acceptance rate which is 8% i.e for every 100 applicants only 8 are admitted.
Meeting GPA and SAT/ACT requirements are very important for getting into a college.
The average GPA is 4.13. This means you need nearly straight As in all your classes to compete with others.
The average SAT score is 1520 on 1600 SAT scale. The score makes MIT extremely competitive for the SAT scores.
-Avg ACT score is 34. Taking ACT tests, you are at the huge advantage as it offers 10 tests, in which you will be required to send you the highest of those ten tests.
Hope this helps.