Dragon Ball Z: Shin Budokai

Dragon Radar mini-game
At the main menu, press L and "Dragon Click" will appear on the Dragon Radar. Press R to play a mini-game where you must press R repeatedly before time expires.

Dragon Player sound test
Successfully complete Dragon Road mode, then press L at the main menu. "Dragon Player" will appear on the Dragon Radar.

Start transformed
While selecting a transformed character at the selection screen, hold R.

Gain energy
Press Select in Practice mode to gain energy immediately.

Adult Gohan (Super Saiyan 2 form)
Defeat Broly in Chapter 2-6 of Dragon Road mode to unlock Adult Gohan (Super Saiyan 2 form).
Adult Gohan (Super Saiyan form)
Defeat Frieza in Chapter 1-8 of Dragon Road mode to unlock Adult Gohan (Super Saiyan form).

Cell (Super Perfect form)
Defeat Cell in Chapter 2-5 of Dragon Road mode to unlock his Super Perfect form.

Gogeta
Successfully complete the last chapter by taking the bottom path to unlock Gogeta.

Goku (Kaioken form)
Defeat Krillin in Chapter 1-2 of Dragon Road mode to unlock Goku (Kaioken form).

Goku (Super Saiyan 2 form)
Defeat Fake Goku in Chapter 2-2 of Dragon Road mode to unlock Goku (Super Saiyan 2 form).

Goku (Super Saiyan form)
Defeat Janemba in Chapter 1-9 of Dragon Road mode to unlock Goku (Super Saiyan form).

Gotenks
Defeat Gotenks in Chapter 1-4 of Dragon Road mode to unlock him.

Gotenks (Super Saiyan 3)
Successfully complete Chapter 3 in Dragon Road mode to unlock Gotenks (Super Saiyan 3).

Gotenks (Super Saiyan form)
Defeat Gotenks in Chapter 1-5 of Dragon Road mode to unlock his Super Saiyan form.

Janemba
Successfully complete Story mode to unlock Janemba.

Majin Vegeta
Use SS3 Goku to defeat Vegeta in Chapter 4 of Dragon Road mode, then complete the rest of the chapter to unlock Majin Vegeta.

Piccolo (fuse with Kami Form)
Defeat Cell in Chapter 2-1 of Dragon Road mode to unlock Piccolo (fuse with Kami Form).

Pikkon
Defeat Janemba in Chapter 2-9 of Dragon Road mode to unlock Pikkon.

Vegeta (Super Saiyan 2 form)
Defeat Janemba in Chapter 2-7 of Dragon Road mode to unlock Vegeta (Super Saiyan 2 form).

Vegeta (Super Saiyan form)
Defeat Android #18 in Chapter 2-3 of Dragon Road mode to unlock Vegeta (Super Saiyan form).

Vegeto
Successfully complete the last chapter by taking the top path to unlock Vegeto.

Card sheets
Get a "Z" rank (by winning all fights quickly with most of your health) on the indicated chapter to unlock the corresponding card sheet:

No. 13: Chapter 1
No. 14: Chapter 2
No. 15: Chapter 3
No. 16: Chapter 4
No. 17: Chapter 5

Round two announced instead of round one
Switch the language to Japanese. While playing the game, it will say round two on the first round.