nowadays for DS saves you only require a 3ds with cfw
you can still do it with a DS and a slot 1 flashcart like a DSTWO, the tools are still available (and i still have them anyway)
but with a hacked 3ds it makes the job simplier and doesnt' require a flashcart
to hack 3ds you can follow the guide on my signature
as for GBA games (sappire, ruby, emerald, firered, leafgreen) you need a DS (fat or lite)
only theese 2 consoles got the gba slot.. and you need the flashcart to launch the tools on NDS
i think there was ways to do it with a GBA and a special cable, but i have no info about this, however, getting the ds lite+slot 1 flashcart is the simpliest solution for the gba games
(get a dstwo, it's the best NDS flashcart)