Use these at the Figure Vending Machine in Access Tunnel E-1.
You can attempt to complete these challenges as the game progresses whenever you want. You can view your unlockables by going to the Sky Room, which Nana will transport you to after Chapter 3.
Go to a place where you can battle a Preon Nurse. Destroy all enemies EXCEPT the Preon Nurse. During the Preon Nurse's turn you'll see a message that says "Preon Nurse surrendered" and it WILL execute an All Life Gain 25 to your active party formation.
There are a couple of secret areas you can get to by deploying mechanaloids to certain areas. Here's the areas.
These are Extra Hyper modes of X and Zero. They are very strong! and will make the game easier. Before you do this make sure you have the Medal Key and the Tianna Key. They can be acquired by Deploying Mechanoloids in The Tianna Camp and The Medal Ore Plant Areas. once you have them make sure you follow these instructions.
After you have beatened the game and gotten the Central Key...Go to The Central Tower, and go to the E-1 section. Follow your path down until you reach a locked door, the Central key should open it. Then you will be in the Special Area. Go down and you will see a Human Reploid, and will challange you to a fight. BEWARE he is tough. his name is Onetail. After you have defeat him go down again and you will see another Human Reploid. He will be Twotails. Go on until you have defeated Eighttails. After that go down and The Secret Vending Machine will be there blocking a door.