Normal ending: Play through story mode, only using Sion.
Wong's ending: Play through story mode, only using Kou or Volt. However, use Sion when fighting Dauragon. Sion will think about his master.
Kaldea's ending: Do not use Sion when you get separated. Use Sion in the ship when fighting Kaldea (the panther) and in the final fight with Dauragon. Sion will remember what Kaldea said.
Dominique's ending: Use Sion when you get separated, when fighting Kaldea (the panther) in the ship, and when fighting Dauragon to see Dominique's story.
Game Shark Codes
Master Code (Must Be On) EC878D98 1456E60A
Infinite Bouncer Points 1CAC4390 1455692C