Battletoads Wii is 100% fake, unofficial video game that originated in 2007 when 4Chan made calls to several GameStop stores for Battletoads Wii, Battletoads II, and other games from the franchise.
Due to these calls, there is an article about it on Know Your Meme. There is also a site where you can preorder Battletoads Wii: BattletoadsPreorder.com. there is a phone number listed there allegedly to preorder the game,
It has been recently announced by Rare that they have sold the rights to the Battletoads franchise to Retro Studios.