Nintendo has finally ended the speculation and confirmed that DLC Pack 3 for Kirby Star Allies is a thing. It's set to release Nov. 30th, 2018 in Japan, and is going to include a new mode, new stages, as well as the Dream Friends Taranza, Magalor, & Susie
The new mode is called Another Dimension Heroes, which is a challenge mode where Kirby and his Dream Friends solve puzzles in another dimension. Their goal in this mode is to collect “Friend’s Hearts.” You'll have to take on "Another Bosses," which are meaner variations of bosses that appeared previously. At the end of the mode, you'll have to battle with the Jambastion mages.