Have a file of Twisted Metal Head-On for PS2 and you can unlock Agamo's Sweet Tooth skin. If you don't have the file, a gameshark or in game code (Mega Unlock) will also do the trick.
Capitol Level
Spend 85,000 Battle Tokens to unlock the Capitol level.
Earning Battle Tokens Quickly
In order to purchase everything in the game, you'd normally have to play through the single player portion multiple upon multiple times. Not so. You're actually able to load a saved game without reverting back to the number of tokens you had at the time of the save. Any tokens you earn will always stay with you and add to your total, regardless if you load a saved game. You can also change the difficulty level and play a saved game at that new setting, which will earn you more tokens.
The best way to take advantage of this is to play all the way through the single player game on any difficulty setting, making sure you save when you reach the last boss. The last level gives you far and away the most tokens, and once you get the pattern down it's not an overly difficult battle. Every time you load that level, beat it and then save the game, your Battle Token total will increase by a nice amount.
You should earn a minimum of around 30,000 tokens for beating the last boss on Easy level, 45,000 on Medium, and 60,000 on Hard. Once you're able to beat Cerebulon on Easy mode, bump it up to Medium and then Hard difficulty. The fight normally takes around five minutes if you can beat him without having to continue, so it won't take long to earn enough credits to buy everything in the game.
Earthquake in Baytown
To activate an earthquake in the Baytown Level (not the mini version) crush every building as low as possible. The whole town will shake for a while and a giant pit will open up.
Impale
Grab any pole or radio tower and throw them at your opponent. If you score a hit they cannot move for a while. If you are impaled, tap SQUARE repeatedly to escape.
Make a Tsunami Wave
To make a title wave on the tsunopolis level look for a flying saucer floating over the water. Jump on one of the buildings closest to the flying saucer. Then throw an object at it. Make sure you are on a building or you will get hit by a wave.
Making-Of Video
Complete Adventure mode as Zorgulon or Raptros.
Mini Baytown Level
Spend 65,000 Battle Tokens to unlock the Mini Baytown level.
Play As Zorgulon
Spend 200,000 Battle Tokens to unlock Zorgulon.
Preytor Parasitism
First use parasite (triangle+circle) then press square(2), triangle, square, triangle, square, triangle(2).
Raptros
Purchase For 200,000 Battle Tokens In Unlocks Menu.
To unlock Sweet Tooth as a playable character, begin the game with a completed save from Twisted Metal: Black on your memory card. Sweet Tooth will be available as Agamo's fourth costume.
Volcano Level
Spend 45,000 Battle Tokens to unlock the Volcano level.
Zorgulon
Purchase For 200,000 Battle Tokens In Unlocks Menu.