Because SRW BX is a Japan-exclusive title, standard 3DS consoles are and cannot run it without modification.
Navigate to SD -> cias , select your game, and choose . Super Robot Taisen BX 3DS CIA & Decrypted (JPN)...
If you are using an emulator like Citra , you generally need files. Because SRW BX is a Japan-exclusive title, standard
Once finished, the game will appear as a gift icon on your Home Menu. select your game
