My Wife is in India and she will be joining me later. She already has a H4 visa. I am on H1.

I need to apply for her Tax ID number. As she is in india, can I notoriae her visa copy in India and then attach it with W7 forms?

Have the copies notarized by a foreign notary. Then take to the Ministry of External Affairs for certification. A certification will be issued in the form of an "apostille," which will be attached to the copy of the doucment.
The apostille must stay attached to the copy of the document when it is sent to the IRS.