"Deadly Alliance": Attack Opponents Before the Fight
Unplug your controller when the game begins to load in your GameCube, and then plug it back in once the game has loaded and the home page appears. You will now be able to fight defenseless opponents before the onscreen "Fight" command appears.
"Deception": Win With an Unblockable Move
Press the following sequence of buttons on your control pad to perform a special move: "Up" three times, "Down," "Up," "Down," "X" twice, "Y," and then "B" twice. This move will work against any opponent apart from Scorpion, and it cannot be blocked. It will also drain half of your opponent's energy, so you can win a fight just by using this move twice.
"Deadly Alliance": Collect Unlimited Koins
Create two new player profiles. In Konquest mode, complete the initial mission with each character to begin earning Koins. Exit Konquest mode, begin a new game in Arcade mode and start a fight with both characters. Gamble on the fight before it begins by pressing "R." You cannot see which Koin types have been bid, so press the following sequences on your control pad to gamble with the desired Koin types: Press "Right" and "Up" to bid with Onyx Koins. Press "Right" twice followed by "Up" to bid with Jade Koins. Press "Right" three times and "Up" to bid with Ruby Koins. Press "Right" four times and "Up" to bid with Gold Koins. Press "Right" five times followed by "Up" to bid with Platinum Koins. Press "Right" six times and "Up" to bid with Sapphire Koins.
Once both players have made a bid, player one should bid again then win the fight to receive all Koins that have been bet on the fight. However, player two will not loose any Koins, so you can fight with both players to win up to 40,000 Koins of each colour. You won't need more than this to unlock all of the Krypt secrets.
"Deception": Unveil Characters From "Mortal Kombat 3"
Select to fight in the two-player mode, choose any two fighters, and then choose to fight at the Portal arena by pressing "R." Once the fight has begun, you can see characters from the "Mortal Kombat 3" game in the destiny pillars. Visible characters include Liu Kang, Smoke and Sub-Zero. Please note that you cannot fight with or against these old characters.