One Piece: Grand Battle

Mini-game mode:
Successfully complete the game.

Axe-hand Morgan Statue:
Successfully complete level 1-3.

Billow-a-bike:
Successfully complete level 6-3.

Cat's Claw:
Successfully complete level 3-3.

Chakram:
Successfully complete level 3-2.

Chouchou's Dogfood:
Successfully complete level 2-2.

Elephant Tuna:
On level 6-1, have Sanji talk to a woman.

Free Food:
Successfully complete level 4-2.

Gas Mask:
Successfully complete level 4-3.

Gum Gum Fruit:
Successfully complete level 2-3.

Hatchan's Octopus Trap:
Successfully complete level 5-2.

Lollipop:
Successfully complete level 4-3.

Mackerel Head One:
Successfully complete level 4-1.

Map of the grand line:
Successfully complete level 2-3.

Master of the Near Sea:
Successfully complete level 5-2.

Shigure:
Successfully complete level 6-2.

Special Buggy Ball:
Successfully complete level 2-3.

Straw Hat:
Successfully complete level 4-3.

Tooth Gum:
Successfully complete level 5-3.

Usopp's Sling shot:
Successfully complete level 3-3.

Wado:
Successfully complete level 1-2.

Zolo's Stomach Band:
Successfully complete level 1-3.

Alvida's pirate flag:
Defeat Alvida in level 1-1 then again in level 6-1.

Arlong's pirate flag:
Defeat Arlong two times.

Black Cat pirate flag:
Defeat Kuro two times.

Buggy's pirate flag:
Defeat Buggy two times.

Cook pirate flag:
Get Sanji and talk to Chef Zeff in level 4-1

Kreig's armada flag:
Defeat Don Kreig two times.

Navy flag:
Defeat Axe Hand Morgan or Chaser the two times.

Red Hair pirates flag:
Successfully complete Boss battle mode under all difficulty settings.

Straw Hat pirates flag:
Unlock all other flags except for the Red Hair pirates flag.

Veggie pirate flag:
Use Ussop to get behind the Veggie pirates in level 3-2.

Sound test:
Successfully complete the game and get the treasure key. Then, collect all mini chests and talk to Gaimon in Syrup Village 2.

Luffy power-ups:
Get the indicated amount of money to give Luffy the corresponding power-up.

Gum Gum Fruit (learn G.G. Balloon): Get 25,000,000
Master Of The Near Sea item: Get 100,000,000
More Deadly Techniques (Super bar increased): Get 65,000,000
Raise Life Limit (Health bar increased): Get 45,000,000
Raise Life Limit 2 (Health bar increased): Get 120,000,000
Straw Hat (learn G.G. Spear): Get 70,000,000