Its depended on what flash cart you have. But in general you will still need an emulator if you have flash cart for GBA. Or if you mean you have a GB/GBC flash cart then you can use it and play as normal GB/GBC games. ANd do not forget you need GBA not a SP/Micro/NDS/L.
I have an EZ-Flash III and it will play GBC games on my SP but I believe it usese some kind of emulator..
The emulator approach is necessary since GBA flashcarts are not backwards compatible with GBC since the consoles are completely different architecturally. It's possible for such a thing to exist but it doesn't and probably never will. The other two options are: -GBA flashcart + bridge adapter (which adds GBC bankswitching and GBC->GBA address translation) -GBC flashcart used on a GBA
yeap, the way memory is read differently and the voltage is different. +10G to Calpis, he can now purchase the hotel by the sea.