Historically, Nintendo's official Wii Shop Channel allowed users to purchase and download games directly to their Wii console. Although the shop is no longer active, some games can still be purchased through it if you have a working internet connection on your Wii.
Distributing or downloading a full system NAND containing copyrighted Nintendo software is generally considered illegal piracy. 2. How to "Download" Your Own NAND (The Safe Way) nand wii download link