Hey Madhu, as you know, during the JEE Mains registration you have options of either opting for "appearing" or "passed" class 12. Thus, while applying in the second case you would need to upload your marksheet which fulfils the minimum marks criteria of 75 percentile marks. As in your case, you would most probably need to first surpass the threshold marks and then apply with a valid marksheet the following year.

Even if it does happen that they won't need it during Mains registration, you still would have to furnish it during the counselling process. So it's better be safe than sorry and keep yourself ready with a >75% marksheet during the registration. And after you crack the exam you can try exploring the best colleges at your rank here: https://engineering.careers360.com/jee-main-college-predictor?utm_source=qna&utm_medium=jee_cp

Hope it helps.

All the Best!