In Which Case Status changed to RFE?

In which case the H1B status changed to RFE? WHat are all the necessary documents need to send to Get approval without RFE? In my account all applied H1B candidate got RFE!

There should be strong justification about the client’s requirement and the unavilability of the resource for that requirement in U.S. Strong documentation is required for employer’s requirement and employee relationship,your suitability for that position etc.