hello aspirant!

yes it is necessary to have admit card for applying the JOSAA 2020.

here are some other requirements for that...

• provisional seat allotment letter,
• admit card of JEE
• scorecard of JEE
• date of birth proof{class X marks sheet}
• three passport size photographs identical to the one uploaded during during JEE registration.

hope thsi helps, all the best for your future.