Hello.
For GUJCET exam candidate must have passed his/ her class 12th with minimum aggregate 45% for general category (40% for SC/ST/SEBC/EWS ) , with physics and mathematic as compulsory subject and your 3rd subject maybe chemistry/computer science/biology/vocational course.
For more detail you can refer below link;
https://engineering.careers360.com/articles/gujcet-eligibility-criteria
Best of