Stop downloading NDS ROMs for a 3DS game. Go to your local used game store, buy a used Nintendo 2DS for $40, and buy the Ultra Street Fighter IV: 3D Edition cartridge for $15. You will have a black-screen-free, lag-free, 60fps fighting experience.
There is no patch. There is no cheat code. There is only the hardware reality. If you found a file that claims to be "Street Fighter 4 NDS (Patched 100% Working).zip" - delete it immediately. It is either malware or a renamed copy of "Fighting Fantasy: The Warlock of Firetop Mountain." You have been warned. Street Fighter 4 Nds Rom Download Fix
Let’s address the elephant in the room immediately: Stop downloading NDS ROMs for a 3DS game