This question has probably been answeared millions of times but I just can't seem to find the answear. If i want a slot-2 device Just for playing gba roms, do I also need a slot-1 device?
No!!! Let me explain. There is a device called passme this is however for running nintendo ds roms off of the slot 2 on the nintendo ds. If you are just running GBA OR GB files all you need is a movie player i recommend looking around and seeing what you can get one for it is called a gba movie player dont let the name fool you it does more then play movies. A lot more.
if you want a slot 2 device to play GBA roms on a DS console Lite (without a slot 1 device), then i suggest you get a 'Elink Flash Card 1G' you can buy it from here but be warn its from Hong kong so delivery takes about 10 days.