Mario and Luigi 3: Bowser's Inside Story with cheats.

I need something (not action replay) or a rom with built in cheats for the game. Or maybe, something like pokesav.

You won't get anything like that. Only way is to use action replay codes (you can just get a cheat database from http://cheats.gbatemp.net/ ).

If you use a flashcart, get a database from http://cheats.gbatemp.net/, use whatever one is specifically for your device at http://cheats.gbatemp.net/files/Credits%20and%20Help.txt If it's been patched, you will most likely need to change the GameID stored in the database to match with the ID in your ROM, open the database with R4CCE, find the game entry, click the ... button and load your ROM. Save the database. If emulator, get the codes manually from the database using R4CCE and import them using the emulator. A ROM can be patched with AR codes however, use a program like DSATM to do so.