There is no specific visa called Spouse visa for India. For any foreigners married to Indians, you can get an Entry visa (X) through any of the FRROs in India.
This visa doesn’t give you any rights to be employed or do business, but you can stay for a long term in India on this visa. And you can open a bank account, as well as apply for a PAN card and Aadhar card.
And after being married for more than 2 years, you can apply for OCI Card.
You may have to fill up the proper details in your application for OCI which would be considered on merits.
Note that while it is possible to get married on an online visa for India, that’s usually issued for 90 days.
FRRO recommends that you start the conversion process at least a month before your current visa expires. It’s normal for the conversion process to take 3 weeks or more.
You get married under special marriage act and obtain a marriage certificate which is an essential document
Another important document is is letter from yourt partner.
Your Indian partner gets a notarized affidavit saying that he/she will take full financial responsibility for you. This letter should have both of your names, passport numbers, etc and he/she has to sign it.
Besides, the foreigner have to get an affidavit that says you will not get employed or do business while in India, and that you want to convert your visa to a spouse visa.
A rent agreement or utility bill will totally work. In case, you are staying in a hotel or Airbnb, you can get a Form C.
The above are few requirements that you should obtain for this purpose.