Choosing the correct Income Tax Return (ITR) form for share trading depends on the nature of your transactions. If you're an individual or HUF with capital gains/losses from delivery-based trading that isn't your primary business, ITR 2 is generally sufficient. However, for intraday trading, or trading in Futures and Options (F&O), you'll need to file ITR 3. This also applies if you combine delivery-based trading with F&O or intraday activities, or if share trading is part of your overall business.
If assessee is individual/HUF and there is Capital gain/loss, then ITR 2 is sufficient. This will be when you do trading on delivery basis and it is not your business.
If assessee is individual/HUF and has income from intraday trading (i.e. without delivery) or has traded in Futures and Options, then ITR 3 will be applicable.
If individual/HUF assessee does delivery based trading, and/or FnO and /or intraday trading then itr 3 will be applicable.