What are GST Registration Documents?
The documents for the GST registration process include a

PAN card
Proof of business registration identity
Photographs and address proof of persons in charge.
Business’ address proof
Bank account statements/Cancelled Cheque/ An extract from Passbook.
Letter of Authorization for Authorized Signatory for Proprietors/Partnerships 
Board Resolution for Appointment of Authorized Signatory for Companies

What is the address proof for GST Registration?

Consent letter (In case of consented or shared premises)
Electricity Bill
Legal Ownership document
Municipal Khata copy
Property Tax Receipt
Rent/Lease  Agreement
Rent receipt with NOC (In case of no/expired agreement)