Complete three challenges in the Ready or Not Mission to unlock a special loading screen. That's where your clue to finding the Secret Hidden Battle Star will be. If you look carefully at the image, you will notice an engraving in the stone just above the doorway. It is on Tomato Head that you'll find the precious star. Grab your glider and head for the location shown in the map below.
Map
You will have to head west of Pressure Plant, below the volcano. This is where the Tomato Temple is located. Try to land directly on the Tomato Head statue. It is quite difficult to climb, and if you land next door, you will have to build spiral stairs to access it.
The Secret Hidden Battle Star is precisely placed on the small growth on the top of the tomato!
Once again, we suggest you to play in Team Rumble mode, which will give you all the time you need to find the star without taking the risk of dying.