DDRMAX - Dance Dance Revolution 6th Mix cheats and cheat codes for Playstation 2

Boost mode
Press Left, Right, Down, Up at the song selection screen.

View song list
Go to the song selection screen, hold Left + Right + Start. 
Select one of the category letters to view songs.

Unlock Candy
Complete the MAX 300 extra stage and reach minimum an "AA" rank.
This will unlock the Candy bonus stage. Finish this bonus stage 
to play as Candy.

So In love song
Clear 20 stages in arcade mode

Kind Lady song
Clear 40 stages in arcade mode

Indicating the groove value of each song:
Choose a difficulty mode, after hold Start just before the song 
selection menu appears. If timed correctly, you will see a numbers 
on the groove radar.

Unlock MAX 300 in arcade mode:
Clear 100 songs in heavy mode.

Extra options
After selected a song at the song selection menu, hold Start. 
or
Select a song at the selection screen, after hold Circle.

MAX 300
Finish the final song in heavy mode and reach an "AA" rating.
This will unlock the MAX 300 bonus stage in heavy mode. 
Finish this bonus stage to unlock MAX 300 in arcade mode.