Tekken Tag Tournament

Fight As Angel:
Beat the Arcade Mode until Devil becomes unlcoked. At the Character select screen, highlight his screen and press Start.

Fight As Tiger:
At the Character select screen, highlight Eddy's screen and press Start.

Gallery Mode:
Unlock Devil to access the gallery mode.

Jukebox:
You can unlock the Jukebox by bowling a score higher than 200 points during a game. Once you've done that you can hit start and access the bowling menu. Now, choose Bowling Options and choose your song.

Knockout Dr. B:
In Tekken Bowl, if you aim at Dr. B. in the background you can hit him and get a K.O.

Secret Characters:
Beat the game to unlock each secret character, which are opened in this order:
Kunimitsu
Bruce Irvin
Jack-2
Lee Chaolan
Wang Jinrey
Roger & Alex
Kuma & Panda
Kazuya Mishima
Ogre
True Ogre
Prototype Jack
Mokujin & Tetsujin
Devil and Angel
Unknown

Start Match With Second Character Selected:
Hold Tag and press Start. Continue holding the "Tag" Button until the match starts.

Tekken Bowl Mode:
Unlock Ogre to access Tekken Bowl Mode.

Theater Mode:
Beat the game one time to unlock the Theater Mode.

Unlock Armor King's Hidden Costume:
Select him as your first character and beat the game in Arcade Mode. Now, you can access his costume by hitting the Start Button.

Unlock Ling's FMV sequences:
To view two FMV sequences featuring Ling, beat the game with Ling one time, then beat the game a second time with Ling in her School uniform. 

tekken 5

Releasing All Characters:
Keep beating Story Mode with different characters until everybody but Devil Jin is released. There is no hidden 'off screen' characters. What you see is what you get.
Submitted by: Tigro

Unlockable: Devil Jin:
To play as Devil Jin, you must complete Tekken: Devil Within mini-game.

Unlockable: Characters:
Anna Williams: Beat Story Mode two times
Baek: Beat Story Mode three times
Bruce Irvin: Beat Story Mode 4 times
Kuma: Beat Story, Battle or Time Attack mode 5 times
Ganryu: Beat Story, Battle or Time Attack mode 6 times
Heihachi: Beat Story, Battle or Time Attack mode 8 times
Mokujin: Beat Story, Battle or Time Attack mode 7 times
Roger Jr.: Beat Story Mode with Kazuya .

Gaining Ranks Quicky:
In order to gain ranks quickly you must play opponents of the same rank as you are, same as it is in the arcade version. When defeating CPU opponents of the same rank as your character it usually only requires 3 to 5 wins to get a promotion.After your fight has ended in Arcade Mode you can select on of 3 opponents with the directional pad, you can't always select an opponent with the same rank but do so when one is available. You;ll have your character rank maxed out in no time.

Kill a Frog:
In the Secret Garden Stage. If you look closly at the ground some where you will notice there is a Frog. If you or your opponent gets knocked in the air and lands on the frog it while die and its angel will float upward.

Getting Expensive Items For Free:
That's right, you can get a bunch of the high priced items for free when you play 'Devil Within' a second time after you have already completed the quest. Various expensive items will be scattered around throughout the game.

Activating Theater Mode:
The Theater Mode gets opened up after you beat Story Mode once with whatever character. At that time you are able to listen to the stage soundtracks, view the movies of the character you just beat Story Mode with and the attract movies (Arcade Intro, PlayStation2 Intro, and E3/TGS trailers). As you beat Story Mode with each character the movies will become available in Theater Mode. Getting all movies requires you the beat Story Mode with both Kuma and Panda as well as Christie and Eddy.

Hidden Story Mode Interludes:
Don't always be quick to defeat the Story Mode interlude opponents, in some cases when you lose you get to see a different movie as part of the story.
Submitted by: deadmaster

Earning Game Money:
You earn money in Arcade Mode, if you play higher ranked CPU opponents you will be rewarded with a higher amount of G after defeating the opponent. The money earned per fight in Arcade Mode ranges from 800G to about 4000G. In Arcade Mode you will also encounter random roulettes which multiply your winnings. The fastest way to get some money in the bank at first is to unlock the endingd for all characters by completing Story Mode with everybody. This gets you 100,000G per character for the first time through only.You can also collect money while playing 'Devil Within' and are rewarded an extra 100,000G upon completing the quest.

tekken 4

Play as Eddie Gordo:
Defeat story mode with Christie and select her again with the circle button to play as her teacher Eddie. 

Play as Miharu:
After defeating story mode with Xiaoyu, select her again with the circle button to play as her schoolgirl buddy Miharu. 

Play as Panda:
Choose Kuma with the Circle or Triangle button to play as Xiaoyu's pet Panda. 

Play as Schoolgirl Xiaoyu:
After beating the game with Xiaoyu in story mode, select her again with the triangle button to play in her academy uniform. 

Play as Violet:
Select Lee with the circle button to play as his alter-ego Violet. 

Unlock Dojo Stage:
Conquer all four Tekken Force stages to unlock the Dojo level. 

Unlock Theatre Mode:
Beat story mode once with any character