In Ben 10 Ultimate Alien: Cosmic Destruction for the PS3, PSP, Xbox 360, and Wii, there is a cheat code you can enter that will allow you to select any level to play on, even if you haven’t unlocked it yet.
Note that once you turn on cheats, you won’t be able to get any achievements/trophies on that saved game again. You’ll have to either start a new game, or go back to a previous save.
To enter cheats, go to the main menu or pause the game and select the Cheats option from the menu, and enter LEVELS as a cheat code to turn on the level select option.