Hi aspirant

You will require several documents like:

3 Passport sized photograph that you have uploaded while JEE mains registation .

Provisional seat allotment letter that you can get if you will apply for couselling .

Candidate undertakings in prescribed format.

Fee acceptance reciept.

Photo identity issued by government/class 12 admit card.

JEE Mains admit card

JEE Mains score card

Birth Certificate

Class 12 admit card ,class 10 admit card 

Result of class 12, result of class 10.

Medical certificate

Category certificate if any in prescribed format.

Passport - For Indian nationals qualifying exam from Nepal/Bhutan

PWD certificate if applicable.

OCI certificate if applicable

EWS Certificate if applicable

You can read more about counselling procedure here:https://engineering.careers360.com/articles/josaa

Hope this was helpful.