I just found this on gamespot, its from august 9th 2005.
Comic Korokoro also unveiled first details on Pokemon Rangers, which the magazine announced last month without citing any game information or release platform. As it turns out, Pokemon Rangers will be an action RPG for the DS. The player will take the role of a Pokemon Ranger, a person that fights to preserve nature and wildlife by using Pokemon. Pokemon Rangers will be released next year, just prior to Pokemon Diamond and Pearl, and it will feature some form of interaction with the other two Pokemon games. Pokemon Rangers is also said to have some connection to next year's Pokemon movie and anime series in Japan.