That all depends on the temperament of the Dwarf kid and what you are wanting to put in with him. I think Lime is correct in what he is saying. I have a DG and a crowntail betta in a 5 gallon, however.... That was after a close and long time observation of how these two conducted themselves in community tanks. In my case, it turned out that each was miserable and afraid of the "Busy body" fish. I've had them in that for nearly a year with no issues.
I think a Cory might be a good idea if you put the snail into another tank. Or just leave it be.