Successfully complete the game, then start a new game with your cleared game file. Enter Sheridan's Mansion to access Boss Rush mode.
Enable RockMan crossover quest
Enter this code while at the eastern solar bank to start the RockMan (MegaMan) crossover quest: Up Up Down Down Left Right Left Right L R L R.
Hard mode
Successfully complete the game.
Solar Sensors
Have the Game Boy Advance game Boktai: The Sun is in Your Hand! in the cartridge slot to get the "Solar Sensor Ver. 1" as an item in the "Valuables" menu. This Solar Sensor allows Aaron or Lucian to replenish their ENE at a faster rate based on sunlight and will charge the Solar Station.
Have the Game Boy Advance game Boktai 2: Solar Boy Django in the cartridge slot to get the "Solar Sensor Ver. 2" as an item in the "Valuables" menu. This Solar Sensor allows Aaron or Lucian to replenish their ENE and LIFE at a faster rate based on sunlight and will charge the Solar Station.
Have the Game Boy Advance game Shin Bokura no Taiyou: Gyakushuu no Sabata in the cartridge slot to get the "Solar Sensor Ver. 3" as an item in the "Valuables" menu. This Solar Sensor allows Aaron or Lucian to replenish their ENE and TRC at a faster rate based on sunlight and will charge the Solar Station.
Sound Data
Have the Game Boy Advance game Boktai: The Sun is in Your Hand! in the cartridge slot to get the "Sound Data (Boktai)" available for purchase at Bulldog's shop in the Acuna Guild for 3000 Soll.
Have the Game Boy Advance game Boktai 2: Solar Boy Django in the cartridge slot to get the "Sound Data (Boktai 2/Zoktai)" available for purchase at Bulldog's shop in the Acuna Guild for 3000 Soll.
Have the Game Boy Advance game Shin Bokura no Taiyou: Gyakushuu no Sabata in the cartridge slot to get the "Sound Data (Shinbok)" available for purchase at Bulldog's shop in the Acuna Guild for 3000 Soll.
Titles
Complete the specified task to obtain the title.
Unlockable - How to Unlock
Adventurer - Complete the Epilogue Tower
Dark Knight - Reach level 99 with Sabata
Gladiator - S-Rank all boss battles
Guardian - Max out the protection capabilities of all sheilds
Gun Master - Raise the level of all of Django's guns to 16
Hunt Master - Defeat one of every type of monster
Shooting Master - S-Rank every Laplace stage
Sol Gunner - Reach level 99 with Django
SP Agent - Clear all quests assigned by the guild
Sword Master - Raise the level of all of Sabata's weapons to 16
Treasure Master - Obtain all accessories
Wanderer - Clear the game on every difficulty
To unlock Django and Sabata Gears
You might have to go through back and forth a lot to get them but it's worth it.
Most of them are from the boss rush.
Unlockable - How to Unlock
Blood-Sucker(Sabata only) - Using Sabata, beat Boss Rush in Gold class with the option "All" and get S-rank.
Day-Walker(Django only) - Using Django, beat Boss Rush in Platinum class with the option "All" and get S-rank.
Eclipse-eye(Sabata only) - Complete Epilogue tower from floors 81-90.
Eclipse-googles(Django only) - Complete the Epilogue tower at the 91-100 floors.
Night-Stalker(Sabata only) - Using Sabata, beat Boss Rush in Platinum class with the option "All" and get S-rank.
Soul-Saver(Django only) - Using Django, beat Boss Rush in Gold class with the option "All" and get S-rank.
Use Boktai Games as Solar Sensors
While the paraSOL weather system may control the climate of the Lunar Knights world, you can directly affect the intensity of Sunlight or Moonlight in the game by slotting one of the three Boktai games into your Nintendo DS's GBA slot.
When you start your game with Boktai slotted, you will be prompted to adjust the Solar Sensor. Afterwards, you will have one of three new items in your Valuables section of the pause menu. These three different Solar Sensors have different effects depending on which Boktai game is inserted in the GBA slot.
Solar Sensor Ver. 1 allows Aaron or Lucian to replenish their ENE at a faster rate, depending on actual Sunlight, and will charge the Solar Station as well.
Solar Sensor Ver. 2 allows Aaron or Lucian to replenish ther LIFE along with their ENE, depending on actual Sunlight, and will charge the Solar Station as well.
Solar Sensor Ver. 3 allows Aaron or Lucian to replenish their TRC (Trance) meter along with their ENE, depending on actual Sunlight, and will charge the Solar Station as well.
Effect - Code
Solar Sensor Ver. 1 - Insert "Boktai: The Sun is in Your Hand!" into the GBA slot of your DS.
Solar Sensor Ver. 2 - Insert "Boktai 2: Solar Boy Django" into the GBA slot of your DS.
Solar Sensor Ver. 3 - Insert "Shin Bokura no Taiyou: Gyakushuu no Sabata" into the GBA slot of your DS.