Not being mentioned in last Thursday's Taiko Blog entry about the next batch of song DLC content (or even the 1st one, for what that matters) is a side feature that comes together with the DLC tracks and is properly mentioned on Atsumete Tomodachi Daisakusen's website!
As a matter of fact, all of the DLC songs made for the latest Wii U release (so far) come with their own set of Tomodachi Daisakusen mini-challenges, meaning that the songs might pop up among the single player mode's friendship-bonding challenges, together with all the default (+ unlockable) tracks! This philosophy also applies to the incoming batch of DLC songs, as the picture above shows.
