Complete the entire game, making sure to save the Titanium Ranger (at the end). After the Credits, you'll have to save and then restart your game. The Titanium Ranger is now selectable.

To be able to skip around the game without beating a thing just select the Codes option from the Main Menu and then select the Enter Code option and enter OMEGA. When you do it right the message "New Code Activated" will appear. Now select the Activate Codes option and press Left or Right to switch the level.

Enter:

SHOWCASE

As a Code to unlock all of the galleries.

Enter:

IMMORTAL

As a code to have unlimited lives.

Enter:

FOREVER

As a code for unlimited continues.