Why?
If you want to just play them, a flash cart with auto-boot ability (so you don't see the menu and it boots straight to the ROM) would likely be cheaper.
Original R4, $2.10
http://www.zhuzhuchina.com/store/r4_revolution_slot_1_for_nintendo_ds_compatible_with_wood_promo.html
2Gb MicroSD, $4.50
http://www.newegg.com/Product/Product.aspx?Item=N82E16820134665
If you want to sell them, you'd need the permission of both nintendo (and other companies involved in making the actual game), and the ROM hackers.