I have a DS and everything i want is already on SS, but no 3DS. I would be able to do it with only one 3DS? You don't need two to trade from Gen 5 to 7?
And I unfortunately will need to get at least one 3DS and I'm assuming one game from each gen. SS is the most recent game I physically own at the moment, so I think I probably need gens 5 through 8 or 9