If you decide to change your information at the time of JoSAA Counselling, you too have to produce the proof. Furthermore, if you have already mentioned General Category in JEE Mains Application Form and the JoSAA Counselling says General EWS, you will be for certain caught at the time you report at your respective reporting centre. And any such act or failure to get the documents verified will lead to the cancellation of admission. So fill the information wisely and honestly.

Check this link to get a better idea about JoSAA Counselling 2019:  https://engineering.careers360.com/articles/josaa-counselling