Hi Mahendra,
I'm not sure I understood your question. But, let me try!
Dynamic report are those which it is possible to add columns dynamically, add some actions, buttons, new tables, new graphics and so on, based on some complex logic, thats it?
If I understood correctly, this is not possible to do using Dashboards, because they are rendered using an IDE that generates Flash Files, and is not possible to manipulate them. Everything with Dashboards needs to be solved in design time.
But using Web Intelligence, I think you will be able to got your functionalities, as you expected. Show us more information, please.