Alter Echo Cheats (PlayStation 2)

When fighting an enemy switch to sword mode and walk up to an enemy
  and press o. when they go up in the air wait till they come low enough
  for you to hit them the press o again this one more time and this time
  when the come down do a shining sword (press square) to finish them
  off fast.
  

To get more "Plasm" points from each kill, get in as many
  consecutive hits as possible.  The more consecutive hits you get,
  the more damage you do and the more plasm you get from each kill...
  which essentially means more powerups faster!

  

As soon as you enter the chamber were the boss is at, he will focus on
  you before shooting a laser beam. Quickly switch to stealth mode and
  turn invisible. while in invisibility mode get as far away from the
  laser beam as you can. After the he has shot the laser he send out an
  explosive bug, jump in it while in stealth mode then (while on the
  explosive bug) switch to gunner mode and fire the bug into the bosses
  mouth. repeat this process about 3 more times. although the bosses
  will send out more bugs. make sure to destroy all but one to shoot
  into he bosses mouth. When the boss freezes and open his mouth really
  wide quickly jump into it in human mode and slash it a couple times.
  wall-lah!

  

 

Enable cheats for 30 seconds:

  up up down down left right left

  restore life:

  L3 + right

  restore time dilation:

  L3 + up