When you start the game chose Gommomon. Use his bubble sheild move to digivolve and kill your opponents. To get ghost mode fight through one plaer mode towards the second one down on the right. Beat him then use his down and b move to use ghost mode

At the title screen, press Right, Up, Left, Down, A, L+R
At the title screen press Y, Right, Down, B, Left, A, R, A, Y
At the title screen press X, Right, A, Y, Left, B, L+R

Just beat the game and/or Character to unlock.

Diaboromon Beat in One Player mode

Neemon Beat in One Player mode

Duskmon Beat in One Player mode

Omnimon Beat in One Player mode

Randomly appears in One Player mode, beat to unlock.

Randomly appears in One Player mode, beat to unlock.

Go through the bracket in a way so in your last stage you beat the one second from the bottom

Go through the bracket in a way so in your last stage you beat the one on the bottom