How can we buy bitcoins in India without linking our pan card and aadhar card?
If you buy through online exchanges, you will have to do it.
If you go through localbitcoins.com, you may find some seller willing to have a cash exchange without identity documents. I think this is soon going to be illegal because this will involve a financial trade and will go against RBIs KYC requirement.
Its a risk but I know people have done that earlier. Things are a lot more open right now and it is best to stick to some legit exchange asking for your KYC and buying from them.
If I may ask, why exactly are you trying to do this? Is it to evade tax or spend some ill-gotten cash you don't want to account for.
My advice, Do it the right way!
If you are genuinely concerned about privacy then earn it rather than buying it with fiat.