Bubble Bobble DS cheats and cheat codes for Nintendo DS

Classic mode Bonus Levels
Go to "Classic" mode title screen, and enter the next code:
L, R, L, R, L, R, Right, Select. Level 20 door will appear. 


Classic mode Power Up! Mode
Go to "Classic" mode title screen, and enter the next code:
Select, R, L, Left, Right, R, Select, Right. 

Alternally you can unlock power up mode, if you collect shoes.
(You will be faster, and make bubbles faster also)

Classic mode Super Bubble Bobble (harder difficulty settings)
First beat the boss in classic mode with 2 players. 
Go to "Classic" mode title screen, and enter the next code:
Left, R, Left, Select, Left, L, Left, Select. 

New  version - Unlocking Lovelun
Finish the new version with Robolun.
She can fire bubbles further than the other characters.

New  version - Unlock Robolun
Finish all 100 levels in the new version. 
After you can select him from the character select menu. 
He really fast, but can't jump as high like Bobblun and Bubblun.

Unlock final 10 levels
Get nine letters. To collect these letters, you have to kill at least
4 enemies in Super Bubble, and get the dropped key.
Then, carry on until the boss of that area and beat it.
Don't drop a huge gem, it will leave a letter. 
Pick up 9 of these (one per boss) to complete the game.