Play against Master and King:
Successfully complete the game using no continues and without losing a
round under the normal difficulty setting to play against
Master in singles and Master and King in doubles in arcade mode.
This can be easily done if the match is set to one round.

Play as Master:
Defeat Master in singles matches in arcade mode.
Master may now be selected in arcade and training modes.

Play as King:
Unlock Master as a playable character.
Then, defeat Master and King in doubles matches in arcade mode.
King may now be selected in arcade and training modes.
Alternately, successfully complete all 22 trial and 24 training levels in world circuit mode.

Special costumes:
Complete the level 3 training missions in world circuit mode before the timer turns red.
In the last ten seconds of the challenge, the timer will turn red from yellow.
Complete it while it is still yellow and you will unlock special costumes.

Underarm serves:
Press A + X + Down at near court or A + X + Up while at far court.

GameShark-Codes
----------------

P1 Quick Win Do Not Use In Training Levels  900806E600000003

P1 Never Win Do Not Use In Training Levels  900806E600000000

P2 Quick Win Do Not Use In Training Levels  EE37148500000003

P2 Never Win Do Not Use In Training Levels  EE37148500000000

Infinite Funds  A33B5C7100000090

All Characters  CEB8E7E3C0705041
                CEBAA7E3E06F1041
                E0705041

All Levels  515477E8C0705041
            515637E8E070F041
            E0705041

Cheats by Dokta T.; Dokta@Newsring.de