"PMU 6", as dubbed by the players and Staff was a change that occurred over time. One of the largest changes from PMU 5, or the "Stone Age", to PMU 6 was evolution, which was added on the date of April 1st, 2009. PMU 6 was replaced by PMU 7 on September 1st, 2010.
Much like its ancestor and descendant, PMU 5, PMU 6 had similar gameplay and the player would move with the arrow keys and primarily attack with the Control button. Very alike to PMU 5, PMU 6 had also included the Stat System. As the player leveled up, the Stat System would allow the player to distribute three "points" to any stat that suited to his or her liking; although the player could increase any stat through various items found throughout gameplay or via trading with another player. During this stage, players were able to recruit Pokémon upon defending them. Evolution was later added. TMs were still able to be bought or found; similar to PMU 5 they had yet to receive the title of "Moves," which did not come until PMU 7. Many of the dungeons previously available do not exist in the newer PMU 7, although some are still being added, such as Mt. Barricade.