You may play all of the boss battles from every board at any time by visiting the Minigames menu. This helps you brush up on your skills for when you face these big baddies during regular Party mode games!
Even Donkey Kong and Diddy’s special minigames are available to play at the Minigames menu, but only after you unlock DK’s Jungle Ruins at the Museum. You’ll find these same sections in the “Game Boards” chapter whenever bosses are encountered, but we figured it’d be nice to put them all in one convenient place for you as well. You’re welcome!