One Piece: Gigant Battle 2 - Shinsekai Cheats - Nintendo DS

Robin/Franky/Brook 2nd Support Attack
To unlock Robin, Franky & Brook pre-timeskip's second support attack, you must level them up to level 3 in Story Mode. Robin's second attack is "Wing", Franky's is "Ballad" and Brook's is "Yahazugiri".

Unlock 1 VS 100 Challenge
The 1 VS 100 challenge consists in a serial of 100 short fights in which you are alone (without support characters) and not being able to recover between each fight (except that after beating 10 characters you'll be rewarded a piece of meat). This is a hard challenge which demands a lot of concentration and coordination along with luck. To unlock it, you have to finish the Thousand Arena Battle Royale and One To One challenges in Shin Sekai difficulty (Very hard) 5 times each with different characters.

Unlock Shin Sekai Difficulty
You can unlock a new difficulty for the two main tournaments of the Thousand Arena mode (Battle Royale & One To One) named "Shin Sekai difficulty" (Very Hard). To do that, you have to finish the tournament in Grand Line difficulty (Hard) with 5 different characters.

Unlock characters
Chopperman - Finish the Thousand Arena One To One in any difficulty with the 45 characters.
Main character support versions - Execute all the character moves in Training mode or finish a Thousand Arena tournament with the wanted character.
Neptune - Connect to the Nintendo WFC and select "Download Content" to unlock a secret level in Story Mode. Finish this level to unlock Neptune.
Shirahoshi - Connect to the Nintendo WFC and select "Download Content" to unlock a secret level in Story Mode. Finish this level to unlock Shirahoshi.
Soldier Docking Emperor - Finish the Thousand Arena Battle Royale in any difficulty with the 45 characters.