Get every dragon:

To get every dragon you have to complete every mission for the virtwyn, chrysalis, and pariah. Make sure to try to complete every single objective. If you fail the mission to win the primary objective or any other objective com back to that mission with a stronger dragon and get the rest of the objectives.

Get All Creatures:

Go to the main menu and press Left, Right, Left, Left, Right, X

Get Invincibility:

Go to the main menu and press Left, Left, Right, Right, Up, Up, X

Get Crystal:

Go to the main menu and press Left, Right, Left, Up, Right, Down, Left, X, X

Get All Multi Player Levels:

Go to the main menu and press Left, Right, Left, Right, Up, Left, Right, X

Get All Objectives Completed:

Go to the main menu and press Left, Right, Right, Down, Up, Down, Down, X