Ummmmmmmmmmmmm I doooooo believe you've gotta have it on an SD card. Or at least I've read that it's infinitely useful if you do. I read you can copy your save, RNG and transfer over any of the legendary mons, then take your SD card out, delete the save, replace it with a copy, and do it all over again as many times as you like. For some reason the game doesn't keep track of how many times you've sent the same mon.