The pot-in-pot method of growing uses a production pot inside another pot which is in ground. This allows you to swap pots easily, and some 20 good reasons why this might be a good idea are listed here.
One other reason I came across was that if you had one production pot sitting on say 4 inches of soil in the ground pot, the latter would reduce perching of water in the production pot improving the aeration of the roots.
I can see this being useful for me as plants wouldn't get blown over in the wind, and watering would be easier if I had frost tender plants in the garden with the rest of the plants. And then I can pull them out for over wintering inside the house, and replace with a winter plant.
So, are there any particular characteristics of the pots that are needed for this to work? Obviously both pots need to drain, be light weight, durable, and you need a light growing medium. Anything else?