Alternate Costumes: 
To change most character's outfits, press START while choosing a fighter. 

Jin and Xiaoyu's Schoolgirl Outfits: 
Play as Jin or Xiaoyu 50 times then press START on them to get school outfits. 

Play as Anna, Heihaci and More: 
To access most of the secret characters, beat the game with 
all regular characters. 

Play as Doctor B: 
To get DOCTOR B, complete TEKKEN FORCE mode four times. 
Each time you finish one set you'll get a key. Collect three keys, 
then defeat Doctor B and he's yours! 

Play as Gon: 
To play as GON, defeat Gon in Tekken Ball Mode. 

Tekken Ball Mode: 
To access Tekken Ball mode, beat the game with all regular 
characters. 

Theatre Mode: 
To access the full movie theater, beat the game with all 22 
selectable characters (including new ones when they are gotten).
Here are some of the harder ones: 

     Gon - beat him in Tekken Ball and in arcade mode.

     Dr B. - beat him in Tekken Force on 4th try and in Arcade mode.

     Tiger - Press start on Eddy at selection.
     This will result in 2 new options at the theater mode - disc and sound.

     Disc - this is an added bonus if you have the past 2 Tekken discs as it 
     allows you to switch to them and view their FMVs.