in order to use DS Download Play with Roms, the receiving DSes MUST have Flashme firmware installed, no other way around it as DS Download Play checks the roms for RSA encryption before downloading, Flashme removes this check. Passcards will not work by themselves to download, the DSes must be flashed with Flashme.
before you go around claming this is true, how do you know it is true? I know for a fact my infomation is true (although not technical at all) because i test what I do first hand. and YOU CAN play download play with a flashed ds and with a unflashed ds. Im no hard core programmer or h4x0r to say exactly what the flashme modifies, but it still works with me. Ill agree not every single game I try works for download play (not sure if its a Supercard SD problem) or a rom dump problem, but the fact that it works for SOME games means that both ds'es DO NOT have to be flashed.