My guess is that they use a computer and that computer has some special program or something. Well if there is someone out there that is really good at hacking they could make a program because your computer knows its connected to something when it is connected to the Wii am I not right. So they could make a program that when you are connected to the Wii it messes it up in any way you want with the program.
Mario Striker Code: 287882 126144
MOH2 User Name: calcalocalo
GH3 Code: 446800821441
Super Smash Bros. Code: 047374795385