Do the achievements to unlock the indicated function:
Solo battles: complete the game to fight battles with partners by yourself
Special option: complete the game two times to unlock the "Special" option in story mode
Neo G Red: complete the game two times
Blue G Red: complete the game four times
Crystal G Red: complete the game five times
Silver G Red: complete the game six times
Gold G Red: complete the game seven times
Silhouette G Red: complete the game eight times
Shadow Neo G Red: complete the game nine times