It is not mandatory for the candidates to have an Aadhaar Card while filling the application form of JEE Main 2019. Candidates will have to provide details of any identity proof like passport number, ration card number, bank account number or any other valid Govt. identity number. You can check the furtehr information with the given below link.

https://engineering.careers360.com/articles/jee-main-eligibility-criteria

In case you have any other query then let me know.

Good Luck!