One Piece Unlimited Adventure Hints

Ok, I bet some people have had problems finding the Golden whale (Which you need to fight the last extra boss: Whitebeard) so I am here to tell the specific location.
Note: You may need to upgrade your rod to a super rod-then upgrade it more with Steel stones.
Ok, first you go to the fossil beach, go to the spot where you first found Zoro and Sanji at the beginning of the game. When your there, head to where that Brown rock is at a spot you have to dash-jump to. There's a fishing spot there, but before you fish, beat those bad guys forthey are quite annoying. Ok, I hope this helps.
Note: You must throw the fishing rod all the way Approx. 150ft. Good luck! (You will need it @_@)

In order to do this, you must have completed 2 previous tasks:

Defeat Overlimit Chopper in Story Mode
Create the Rumble Ball

After achieving those requirements, you will now be eligible to transform into Overlimit Chopper. To do so, you first must be in a boss fight. While in the fight you have to use TWO Rumble Balls (wait for one to run out, heal SP gauge, take another one). While you are using the second Rumble Ball, the enemy has to kill Chopper. Instead of dying, like he normally would, a cinema scene occurs. The scene shows Chopper taking a third Rumble Ball and he transforms into his Overlimit form. He gains a new HP and SP bar. He isn't able to use items.