Confirmed that the white Dice Block is not Boo's. It's the dice block of other party members that add up to your total roll. Oh well.
Anyway, I basically know much of the general information for the rest of the modes thanks to my researching to improve
Mario Party: Star Rush's article in MarioWiki.....
Balloon Bash seems to be like the traditional Mario Party the most except you trigger minigames via touching Coin Balloons, just like in Toad Scramble. In that mode, you can even buy Stars for 10 coins, just by passing a Star Balloon space. The only thing it lacks is a good item roster. This game doesn't really have that good item roster, with only Mushrooms, Duel Glove (Ally Duel and Coin Duel winners are determined by Dice Block rolls rather than Duel minigames, not fun and pretty disappointing), and Warp Boxes.
Coinathlon seems like lots of fun. As you collect coins in specific coin minigames, you move forward. You can obtain items when a meter is filled, and you touch a crystal box holding an item. You can also adjust the number of opponents and laps around the board.
Mario Shuffle is pretty eh. You have two teams of three (six in all) against each other, going against each other on a linear board and you basically have to rely on two Dice Block luck in this mode, but at least you can choose who to move if one of the two has a move favorable number. Hop over opponents when you pass them to make them lose a turn or land right on their space to send them flying back; you can also land on + or - minus spaces to send your piece in a direction.
Rhythm Recital is pretty laughable for a rhythm game, easily the worst mode it seems. It's more like a metronome simulator than an actual rhythm game. That one Blooper boss minigame has better sense of rhythm than this entire mode.
Challenge Tower seems to be a thing where you climb up a tower while landing on colored spaces and avoiding bad spaces. There isn't much information on this one aside from that you can complete a 500 floor challenge, which sounds hard but I don't know how hard it'll be.
Boo's Block Party is your typical puzzle game. You can face off against Boo in an endless mode for a high score.
Multiplayer in this game is the best multiplayer features on 3DS, thanks to Mario Party: Star Rush - Party Guest. This lets you enjoy local mode-like play via app with only one cartridge. That really deserve heaps of praise, especially compared to games like Mario Kart 7 and Kirby Fighters Deluxe where I really hate those single-card restrictions.