In the interest of maintaining a healthy tournament environment, Pokémon Organized Play removes older sets from the Modified format at the beginning of each new tournament season. Each rotation challenges existing players to create new strategies while enabling new players to get into organized play with a minimal investment.
In an effort to increase the depth of the available card pool at early season events, Pokémon Organized Play will forego its standard set rotation for the 2009–2010 tournament season, creating a Modified format with nine regular sets at the beginning of the season, and ending the
season with thirteen regular sets.
The modified format for the 2009–2010 season will consist of the following sets:
Diamond & Pearl, Diamond & Pearl: Mysterious Treasures, Diamond & Pearl: Secret Wonders, Diamond & Pearl: Great Encounters, Diamond & Pearl: Majestic Dawn, Diamond & Pearl: Legends Awakened, Diamond & Pearl: Stormfront, Platinum, Platinum: Rising Rivals, Diamond & Pearl Trainer Kit, POP Series 6–9 Promo Cards, Black Star Promo Cards numbered DP01 and higher.
In addition, future Pokémon TCG sets will become legal as they are released, per the Pokémon Organized Play Tournament Rules.
Pokémon Organized Play will resume the seasonal format rotation with the 2010–2011 tournament season.