Cheats / AR Codes On Flash Carts Most modern flash cart softwares support AR codes, and can use one or more database types. There's no need to use an actual Action Replay or any other cheat device to apply codes to a DS ROM being played from a flash cart. Applying Codes When applying the codes, it's generally done in the properties of a ROM. You'll go to a ROM's properties.settings, choose the cheats option, then check the cheats you want to have applied when you run it. The actual process varies depending on the flash cart you're using, so check the user guide for your cart's software if you're lost. Updating Database As far as updating the cheat database, it's usually as easy as replacing a file on the MicroSD, usually in the system folder of whatever software your flash cart uses. You'll see the cheat database file somewhere (if it exists), you can just overwrite it. Database Types As far as the database, there's a few types (cheat.db, cheat.xml, usrcheat.dat, etc.) but usrcheat.dat is the most widely-used nowadays, since it can easily be edited. If your flash cart was made within the past four years or so, chances are you can use this format, and it's preferred that you do since it's the easiest to keep updated. Downloads The most commonly-used database is maintained at Codemasters Project, but if you just want to download the database you can either use The DS-Scene ROM Tool (which has many additional functions and downloads a few versions), or download usrcheat.dat immediately with this link. Editing If you want to edit the usrcheat.dat database yourself, use R4CCE. There's some instructions here. EDIT: Now that the transition period is up, I merged this with the main FAQ.