Take the monster roster as an example. Shonen Jump reports Dragon Quest Monsters Joker 2 Professional has over 100 more monsters than the original game. Square Enix also created new maps and tweaked the combat system. You can now give monsters in your party the "try various things" command from other Dragon Quest games.
Crosspass battles have been expanded to support three characters simultaneously and a strongest master faceoff over Nintendo Wi-Fi.
Dragon Quest Monsters Joker 2 is slated for spring 2011.