Mario Party
Swing On A Vine
This trick is pretty simple. Go to the mini game house, if you haven`t already, buy the mini game called piranha`s pursuit. After you`ve bought the mini game, then play it.(this will work with any character), While your playing the mini game, when you see a vine press "A" while at the vine. Then it will give you a boost. After you win, if you win, notice that you get extra coins instead of just fifteen.
Credit Goes To: sescott@sprynet.com via N64cc
 Swing On A Vine
 Secret Items
 Bumper Ball Maze 3
 Bumper Ball Maze 2
 Bumper Ball Maze 1
 Secret Boards
 Different Title Screen
 Get Coins Easily
Secret Items
Once you beat Eternal Star, go through the credits and you will have the chance to buy these secret items.
End Credits (100 Coins): Allows you to see the end credits when ever you want.

No Koopa (500 Coins): Bowser doesnt appear on most game boards if activated.

No Boo (500 Coins): Boo doesnt appear on most game boards if activated.

Gumball Machine: All you have to do is buy 30 minigames in the minigame hut. Then you can go to the store and buy a gumball for 300 coins. This will then randomly buy you a minigame that you haven't yet purchased. Great way to save money on the 300+ minigames!
Credit Goes To:Mannzis & XHollywood@aol.com via N64cc

Bumper Ball Maze 3
Once you have set new records on Bumper Ball Mazes 1 & 2, Bumper Ball Maze 3 will become selectable.

Bumper Ball Maze 2
To unlock Bumper Ball Maze 2, you must clear all 50 Mini-Games on Mini-Game Island and then go talk to Toad at the Goal.

Bumper Ball Maze 1
To access the mini-game "Bumper Ball Maze 1," you must reach the goal of Mini-Game Island and defeat Toad in a game of "Slot Car Derby 2."
Credit Goes To: Jim L. Patzer via IGN 64

Secret Boards
Magma Mountain - In order to play in Magma Mountain, all you have to do is to beat the first 6 stages. In these 6 stages, you have to buy things in the shop. After that, you can play Magma Mountain.

Eternal Star - Get 100 stars in Magma Mountain, then a special event will appear. After that, Eternal Star will appear. By the way, after beating Eternal Star, you will see the ending, and some more, special things can be bought in the shops.

Different Title Screen
In Mario Party, the Title Screen will change usually. In order to do that, you have to beat the game with a character, and the character would be the MAIN CHARACTER in the Title Screen. e.g. If you beat the game with Mario, then the Title Screen will change into Mario's.

Get Coins Easily
This codes is very easy, also convient. To use this code, select three of the characters. Then stop at the final round of game and turn all the computer players into 2P, 3P and 4P players, and you can get all the stars and coins.
Credit Goes To: Desmond Choy (cychoy@netvigator.com) via N64cc