As of May 20, 2013, all online services for the Wii and DS are going to be shut down. According to the announcement made by Nintendo of Japan, upon the closure of the said service, Nintendo DS/DSi and Wii users will no longer be able to access online features like matchmaking, leaderboards and online play.
Titles that require a Wi-Fi connection for some component will be reduced to just support on the local level. This however will have no effect on the Wii Shop Channel and Nintendo DSi Shop. Users will still be able to access the shops through Wi-Fi to purchase and download new content.
Additionally several online entertainment channels for the Wii, like Hulu, YouTube and Netflix will also cease to exist. The few Wii owners who have been using their console for Internet browsing or media streaming will have to revert to an alternative solution.
Around 20 Nintendo published Wii games and 40 DS games will be affected by the closure of online services. That list includes big names like Super Smash Bros. Brawl, Mario Kart Wii, Pokemon: Battle Revolution, Dragon Quest 9: Sentinels of the Starry Skies, Fire Emblem: Shadow Dragon, and The Legend of Zelda: Phantom Hourglass.
You can browse through the complete list of titles on the official Nintendo of Australia website.
In a passed statement, Nintendo said: “We at Nintendo sincerely thank our fans for their continued support of our company’s legacy systems. Your enthusiasm for games made for these systems speaks to their longevity, and the passion of Nintendo fans.”
Source: Nintendo Japan