Registration Required or Not - Goods and Services Tax - GST

Dear Expert One of My client is registered under Maharashtra, He has to import the Goods At Mundra Port in the state of Gujarat with Maharashtra GST No in Bill of entry and have to storage in warehouse within Port area after Payment of IGST Custom Duty, after that He has to sale Locally in Gujarat and other state With IGST. Question: Is Registration Required in the Gujarat State ? Can he raised Invoices from Maharashtra ? Can Gujarat GST Department forced him to take GST No in the Gujarat?