I can think of at least two on PC that emulate the game perfectly, Snes9x and Bsnes The DS will never have the power, even with this emulator and the DSTWO.
The only way this could ever be feasibly possible with a DS would be in the hands of a highly skilled coder capable of efficiently getting the MIPS processor of the DSTWO and the ARM7 & ARM9 processors of the DS to work in concert to provide the processing. Even then, that would still be less than 500 MHz of total processing power and 4 MB of RAM to work with. The only real hope of proper SMRPG on a Nintendo handheld would come either from a VC release (wishful thinking) or an emulator written for the 3DS. Even then, that's still not much more total processing power than the MIPS/ARM hybrid coded emulator I wrote about earlier.