Capital Gain applies only when you have a gain on your invested capital. If you have never bought crypto, there is no question of capital gain either. Make sure to accept the proceed of your crypto sales at a current account. Keep note of all the transactions. Pay tax as per presumptive taxation rules. Remember, if the total volume is over 20L INR, you need GST registration.
I am really ignorant in these things, why would you need a GST registration if there is no regulations about it. I am not sure what is presumptive tax, the head ache of filing the tax is done by my CA, the transactions i got from bitcoin are in my personal account and usually split in my family members account to avoid taxation and i never filed them till now due to the grey situation we have.
. Dont bother about GST if your turnover is below 20L INR.