DDR Max 2 uses a unique "point system" to reward you with hidden content (new songs, options, etc.) Every song you clear regardless of difficulty level, including Nonstop mode songs, counts as 1 point. Every 5 points you earn unlocks a new item. So by setting "Max Stage" in Options to 5 and then clearing that many stages each time you play Game Mode, or clearing a Nonstop course with at least 5 songs, you can unlock at least one new item every time you play.
Ok this cheat helps you unlock all the bonuses in the game. But it kinda requires you to have DDRMAX.
-Insert the memory card with a saved game from DDRMAX.
-Go to the option screen in DDRMAX2 and choose "memory card".
-Last select the "Support" option.
I heard this cheat from a friend and so I need to try out myself. =p
To aquire the Endless Mode you must unlock all other bonus songs. Endless mode is when you play through every song without stopping.
In order to get the extra stage(MaxX Unlimited) you need to AA your last song on Heavy.(it canot be on little).MaxX Unlimited will be on reverse,x1.5,dark,and on pressure mode.If you AA that song you will reach one more extra stage called Kakumei.
Another way of getting Kakumei is if you AAA your last song on Heavy.If you pass both extra stages you will unlock both songs!