Many of the games released for said consoles includes some compatibility for the concept, including [the most common] online play, or even downloadable content support (DLC).
Mario Kart Ultimate is the first game to introduce the concept. The online mode includes the Communities included within Mario Kart 7.
The Mushroom Shop included within the game also utilises a beta version of the DLC support, and includes 18 purchasable characters, and 4 purchasable cups.
Mario Kart: Duplicated is known to include DLC support in the game, as it has been revealed that the Nintendo Network II will be fully functional on the day of the game's launch.