Yes, if someone is holding only trading account with us, you have to send a new demat form.
If you are holding an existing demat with IL&FS, send new demat form along with a IL&FS closure request form (this will be updated on our site by monday). Once Zerodha demat is opened, we will send this closure request to ILFS and all stocks will be moved to Zerodha demat free of cost.