???

>>26922817
3ds, x/y and or/as

>>26922817
GBA can play gens 1-3, DS Lite can play 3-5, 3ds can play (or will be able to play) 4-7. Gen 1 is also available on 3ds. Cartridge gen 1 and 2 can't transfer to gen 3; you also need the DS Lite to transfer from gen 3 to 4. You need two DS systems or greater to transfer between 4 and 5. In short, you can play all gens except for 2 on a DS Lite and a 3ds, and be able to transfer.

>>26922817
Buy a 3DS, a Pokemon Bank membership (5 Trumps a year) and the following:
Platinum, Heart Gold or Soul Silver, Black or White, Black 2 or White 2, X or Y, Omega Ruby or Alpha Sapphire.

There you go, you can visit every mainline region with these games (Kanto and Johto in HGSS, Hoenn in ORAS, Sinnoh in Plat, Unova in BW/2 and Kalos in XY) and trade Pokemon from BW/2 onwards to your XYORAS games with Bank.
Sun and Moon come out in November and it's a new region so get that too.