Ultimate Monster was the powerful creature known as D-Mon. This creature was the legendary similar of Pokemon.
This legends say that the power the Six Color Stars to create the legendary, powerfully and strongest attacks creatures. The powerful Six Color Stars wasn't power enough, but it can usable attacks. The destruction of Ultimate Monster shattered into six pieces of Six Color Stars and place to The Master of Shadows. Pete is only playable with Samuel's team members to defeat Shadow Master Bosses.