[Layell]

I'll try to answer your question as best I can but there are some things.

Yeah you could probably do this solo, although you would need two Nintendo DS handhelds. One of them would have to be an original or DS Lite to have a gameboy advance slot.

In terms of completing your personal pokedex this might not be the best plan. Most of the games do have methods of getting a good chunk of every pokemon, it's just in the context of a speed run they are horribly inefficient. I don't want to wait every day or change the clock for the ingame swarms but in the context of a more relaxed player that might only play an hour each day that's more than fine. Since I'm minimizing luck based things such as the swarms and the Safari Zone, and some sidequests and side areas I am limiting tons pokemon that can be caught in each game.

If you just want to personally fill your dex start at the top and figuring out how to get each mon in the games you own. Rather than say, buying the game I wrote that is best then beating the game and catching that pokemon in the area I say and raising it the one or two levels to evolve it, rather than just catching it and raising it say ten levels to evolve it in the game you own.

Heck this isn't the minimum number of games. You can easily go without Black 2, just things like Riolu, Azuril, Latios, and a few others take a bit more time in the others.

If you want them all on one game that actually takes more effort. I'm assuming you want a completed dex on one game. Problem is for things such as the starters you'll probably have at their highest stage, so you'll need to breed them, hatch the egg and level the baby in the second evolution. You can take some time out of it by leveling some mons right before they will evolve twice, that helps. But transferring takes a ton of time. I did most of gen 3 > 4 and I wanted to kill myself. Transfers are annoying, and I did most of them while doing other stuff while watching TV.

Use Serebii and Bulbapedia for helping catch as much as you can, then consider if you need to shell out money for more games. Chances are you may not even have to. Also there is always wifi.