The Pokemon Ranger games on the DS have *actual* DLC missions. Given that this is Pokemon, and that some of the DLC missions allow you to get certain legendaries and send them to a main Pokemon game, there was enough interest in hacking them in that people *did* create ways to add them to your save file, although the program to do so has some problems. See http://gbatemp.net/threads/guardian-signs-mission-injector.265884/
That mediafire link is dead.