This is kind of an odd question. My friend and I have started playing Fire Red and Leaf Green. He is playing his on a DS lite. I am playing my game on a Gameboy SP. How can we battle/trade with each other? I also have access to the original DS.
Your friend would have to get himself a Gameboy Advanced/SP since the DS Lite has no link cable slot. Link cable is the only way to trade/battle in gen 3.