Choose arcade mode, lose a match. Then let the timer run out. You'll have 10 seconds to enter the ultimate kombat code for the character. Only 1 at a time.
Saving- After unlocking them in arcade mode, get to the character select screen. Pause, then exit the game. you'll have them for the rest of the time your playing that time.
NOW, very important, when you start the game up the next time around, you need to FIRST go to the arcade mode. This will load the characters you unlocked. Just wait and get to the character select screen, then exit. Now you can play with the characters online.
IMPORTANT- If you do not go to the arcade mode first, you will erase the characters. Just load and exit, then play online.
Code
Effect
Player 1: HP-5, LP-1, BL-8, LK-3, HK-8 Player 2: same buttons
Unlock Classic Sub-zero
Player 1: HP-4, LP-2, BL-3, LK-4, HK-1 Player 2: HP-1, LP-4, BL-3, LK-2, HK-4
Unlock Ermac
Player 1: HP-4, LP-2, BL-2, LK-6, HK-2 Player 2: same buttons.
Player One-At the Select you fighter screen, pick Smoke and press High Punch, High Kick, Block, Run, and hold away (left) with the joystick simultaneously until the match begins. Smoke will explode into the Human Smoke.
Player Two-Do the exact same thing as Player One, except press Toward (right) with the joystick.
Code
Effect
High Punch, High Kick, Block, Run, and hold away (left)
Player One, play as Human Smoke.
High Punch, High Kick, Block, Run, and hold away (right)