According to our friend Zhenlin over at BMG, the June 2007 issue of CoroCoro reveals new details about the upcoming sequel to Pokémon Mystery Dungeon (ポケモンの不思議のダンジョン).
Sequels subtitled Time Expedition and Darkness ExpeditionThere will be two versions, as before, subtitled Time Expedition (時の探検隊) and Darkness Expedition (闇の探検隊), which will be released this fall. As previously noted, this is the first time that Chunsoft is making a sequel to a Mystery Dungeon game involving licensed characters other than Torneko or Chocobo.
The premise of this game, as suggested by the subtitles, is that of exploration, as opposed to rescue in the original Pokémon Mystery Dungeon. The impetus appears to be a stone fragment which is thought to form the gateway to legendary locations and/or treasure. As before, the player is subjected to a personality test at the beginning of the game, which determines which Pokémon the player will be in the Pokémon world. Among the 16 available player characters are Munchlax, Pikachu, Piplup, Chimchar and Turtwig.
A new game mechanic is guilds. In order to form a great exploration party, the player must train, and to train, the player must enter a guild. The guild master is a Wigglytuff, and its right-hand man is a noisy Chatot. Other guild members include a Bidoof. On the other hand, as in all previous Mystery Dungeon games, the defining feature is the random dungeons players execute their quests in.