THIS IS FOR THE 3DS one: while the game is loading Hold ABXY then a screen will pop up
Agein THIS IS NOT FOR DS its for the 3DS
I've read that if you press... Start, Select, R, L, A, B, X, Y and the center of the D-Pad you wipe the data and restart. If you don't press all the buttons it won't work.
Hope this works for you!