On the last level where you fight Kid Buu, when you start dig (press [Square]) until a question mark appears over your head. Note: You can use any character.
Buy all the red capsules that you can get with the Silver Card.
Make Bulma move in the shop
Press [R2] and she will move.
Continue customizing character
When on Stage 2 on Babidi's ship, you can still customize your character. Before you continue with Stage 2, add a full Senzu Bean onto you customized character. After your one bar of life is gone you will use the Senzu Bean and regain three full bars of life, extending the time that you can "endure your opponent's attacks".
Buy all red capsules that you can get at the beginning. Alternately, have a saved game from the original Dragon Ball Z: Budokai on your memory card.
In Dragon World, do not take the Potara Earrings from the Supreme Kai to fuse into Vegito. Complete the game without taking them.
To unlock the characters easily, try to complete the Dragon World (the real game). About every time you defeat a character, you will unlock the person that you were battling against.
Enter Bulma's Shop. Do not buy anything. Leave and press L1 + L2 + R1 + R2. Do this a few times until your percentage begins to increase. Note: You must have auto-save enabled.
To get a capsule without paying, go to the skill shop, hold L1 + L2 + R1 + R2 and press Triangle to exit. You will get a capsule each time you exit.
Successfully complete novice and adept modes in tournament and save the game to a memory card. Get a different memory card with no file from the game. Complete story mode and go to Mr. Popo's shop. Put the memory cards in slots one and two. Trade the Dragon Ball from the new saved file on memory card two to Memory Card one. Remove both memory cards. Put the memory card that was in slot two into slot one. You will now have all the characters from the saved game file on memory card one.
Enter the Skill Shop while holding down the L2 button. Bulma will talk, but just leave, while holding the L2 button still. Re-enter the shop, repeat the trick over and over and your percent of your Capsules keeps increasing. This also unlocks characters for you, Breakthrough capsules, fusions, everything.
Instead of having to press the P + K + G, press R1 + R2 to transform. This works with all characters who transform in any way. This can be very useful if you want to knock the guard off your opponent while standing next to them.
Buy all the red capsules that you can get with the Gold Card.
Unlock Tiencha, Gocruel, and KibitoShin
Collect the dragonballs and earn the breakthroughs for Goku, Hercule/Sataan, Yamcha, Tien, and The Supreme Kai/Kaio Shin. After that, gather the dragonballs again and earn their fusion capsules.
Restore health during fight
Note: This trick requires two players and Babidi's Spaceship. First, go to Babidi's Spaceship. When asked how many players are playing, select "2P". One of the mini-games involves locking your Ki and Health together. Select that game. You can now recharge your health during a fight. Note: Since this trick locks your Ki and Health together, you can now lose health by using any Ki-draining special attack.
Golden Capsule on level 1
On the first level, where you have to get to the Dragonball before Raditz and Nappa, defeat all the Saibamen that pop up until a red one appears. Fight that one and win. You should get a new capsule for Hercule. Equip the capsule, and whenever Hercule's health drops below one sixth he will now receive a boost of energy. This may require a few attempts
To get Bulma's costumes, get all the Dragon Balls. Then, summon the dragon. If you are lucky, you can get Bulma's costumes. Bulma's costume will change the way that Bulma appears in the capsule shop.
Free Capsule Increase
With a memory card inserted (to save progress), enter an item shop. Hold L1 + L2 and leave. Repeat the process for more stuff.
Gain everyone's Devastation move
At the end of Dragon World, defeat Kid Buu With the desired character to gain their devastation move. For example, Goku's Super Spirit Bomb, Vegeta's Big Bang Attack, Gohan's Super Kamehemehe, etc.
Picking up a Dragon Ball
To pick up a Dragon Ball after it is in the center of the Dragon Ball Radar, just select the character that is on top of the Dragon Ball and press [Square].
When you get all seven Dragonballs you get one wish. Do not buy Bulma's costumes. Instead, you should buy Breakthrough, Fusion, and Potera capsules. Breakthrough capsules take all seven slots but give every move for that person. Others allow secret fusions between people.
Use the following trick to get all the wishes. At the very end when you must defeat Kid Buu you will get one wish after the credits by obtaining all seven Dragon Balls. Before you defea Kid Buu, save the game and exit. Then, copy the saved game file for the game onto another memory card. Start the game again and defeat Kid Buu (again) and get another wish. When done, copy or transfer the capsule that you obtained.