Fill Mushroom Bank Easily
Every time players complete a game, the stars and coins from each human player are put into the Mushroom Bank. However, if computer players are filling in, those coins and stars are lost. An easy trick to accumulate lots of stars and coins is to play a game (or have four computer players play a game) and switch all players to human players in the last round of the game (you can do so by pausing and accessing the options menu). Complete the board and you will be able to keep ALL the stars and coins.
Mushroom Shop Items
You can purchase new game-enhancing items in the Mushroom Shop. Here is a list (the numbers denote the cost):
Plus Block (200): Get a random number of coins.
Minus Block (100): Lose a random number of coins.
Speed Block (200): Numbers 8 to 10 appear on the block only.
Slow Block (100): Numbers 1 to 3 appear on the block only.
Warp Block (200): Players change positions on the board.
Event Block (200): Boo, Koopa, or Bowser will appear.
Mecha Fly Guy (100): Counts rotations of the control stick.
Record (50): This lets you listen to the game's tunes in the Option House.
Talking Parrot (50): Enables a voice test in the Option House.
Lucky Box (100): Get 10 percent interest on coins.
Casino Box (300): Bet your coins and get double or half.