There are 3 different ways one can be banned on the Wii. Nintendo does NOT tell you which of ban type hit you. You have to somehow figure...

First is Wii ID ban. You can find your Wii ID in the address book in the Wii Menu. To change it, you have to reformat your Wii. Alternatively, you can use a Wii ID Changer code to have a different ID just while playing this same game. Permanent solution is to reformat your Wii...

Second is MAC ban. You can view your MAC address in the Wii Internet Options. Unbanning from MAC can be done by changing your internet provider, by using a MAC Spoofer code, by begging Nintendo or by patching the game ISO: https://www.youtube.com/watch?v=GY8I2N_1npA
Permanent and best solution is to write ninty and e-mail...

Third is SN ban. The serial number can be found at the bottom of your Wii. You can unban by getting a different Wii, by begging Nintendo, by using a SN Spoofer code, or by changing your DWC_AUTHDATA, like taught in this video: https://www.youtube.com/watch?v=XxQ7fcKLh6I
You need to delete ALL of your online savegames, in order to get back online. Last mentioned makes up the best solution for SN.

Credits to mainly mdmwii for these information. Here´s his video about some unban codes: https://www.youtube.com/watch?v=GY8I2N_1npA

-x Droiid

they have a few ban types but nitendo sucks becuase they dont even have serquirty lol and they dont even know howto use the freaking machines and computer devices lol ... but i play mw3 and stuff on wii

my wii is so modded if they tried to ban me they get lost in lines of C#