According to press release statements prior to Delta Species-era expansions and information on booster packs, the Holon region was inhabited by humans who wished to search for the elusive Mirage Pokémon Mew. Establishing a city (also called Holon), scientists utilized the unique magnetic properties of the area to produce waves of electromagnetic energy via a large tower in the city center to track the location of Mew. The resulting electromagnetic waves caused the local Pokémon to mutate into abnormal types inconsistent with their genes elsewhere, with their highest evolved forms typically having Metal as a type. The affected Pokémon came to be known as Delta Species.
From various pieces of information and artwork from TCG products, it can be determined that the region is largely forested with a large lake and marshlands to the south. The lake is also bordered by a massive mountain range. The region is presumed to be near the coast, with an island bearing unique crystals some distance offshore, forming the basis for much of the EX Crystal Guardians expansion. Described to be beyond the horizon are a chain of islands where powerful Pokémon are said to reside, which forms the basis for much of the EX Dragon Frontiers expansion.
This listing is of cards mentioning or featuring Holon or Pokémon that belong to the city. Most of these Pokémon are artificial and can double as Special Energy cards when attached to other Pokémon in play.
Holon's Pokémon Cards listed with a blue background are only legal to use in the current Expanded format. Cards listed with a silver background are legal to use in both the current Standard and Expanded formats.
Holon: The main community of the region, nestled in the center of Mirage Forest. From above, the city looks like a giant Poké Ball, with a ring of trees serving as the main border and with a canal that runs through the diameter into two circles that surround the city center. A cobbled walkway circles the land in between the circular canals and border, bridging the waterways. There is also a larger walkway with grand balustrades that leads to the city center. The houses are largely dome-shaped, and many properties have their own garden area or orchard. An observatory and the Holon Research Tower lie at the center of the city.
Areas of interest
The stone formation in the lake
Holon Research Tower: The tower dominates the skyline of the city and was constructed in order to manipulate the unique magnetic properties of the area to produce electromagnetic energy that hoped to aid scientists to track Mew in Mirage Forest. When in operation, the tower can be seen absorbing bolts of yellow energy from three generators that surround it. When seen from above, the tower resembles the symbol used on Metal Energy cards, likely a direct reference to the secondary type of δ Delta Species Pokémon featured in the sets. The tower also provides the set symbol for EX Delta Species.
The mountain range that encompasses the lake, with Aerodactyl in the image
Mirage Forest: The main focus of EX Legend Maker and touched upon in EX Holon Phantoms, this dense forest encompasses the city of Holon and is home to many of the Pokémon that were genetically altered as a result of the electromagnetic energy produced from Holon Research Tower. The southern edge of the forest is dotted with marshes as the land gives way to the waters of Holon Lake.
Crystals growing on the Mysterious Island's beach
Holon Lake: Also featured in EX Holon Phantoms, Holon Lake is a vast body of water that is home to many more δ Delta Species Pokémon. In the lake, there is a stone formation that resembles the symbol used on Metal Energy cards. Perhaps as a homage to the Generation II games, the lake is also home to a ShiningGyarados, similar to the Red Gyarados that appeared at the Lake of Rage.
Mountain Range: Surrounding a portion of Holon Lake is a large mountain range, featuring tall jagged peaks and outcrops. The foothills of these mountains contain boulders with mysterious patterns on them, as well as entrances leading to caves, which are home to fossil Pokémon that have also been affected by the radiation from Holon Research Tower.
Mysterious Island: Described as an island far offshore from Holon, its main feature is large crystals, which naturally grow there and are said to grant special powers if used correctly. Normal Pokémon and δ Delta Species Pokémon cohabit the island, and there is little human activity there. It is the main focus of the EX Crystal Guardians expansion.
Distant Island Chain: Described as being beyond the horizon, these islands are a habitat where natural Delta Species Pokémon thrive. This is reflected in the cards featured in the EX Dragon Frontiers expansion, as fully-evolved δ Delta Species Pokémon remain purely one type, as opposed to being partially Metal-type. It is possible that these Pokémon evolved to become δ Delta Species naturally or the trait was outbred.
A magnetic storm
The weather in Holon is very strange and different from other places due to the electromagnetic waves from the tower in the city center. Magnetic storms may occur. In addition, pressure changes are not uncommon.
In philosophy, a holon is something that is simultaneously a whole and a part, a reference to how Holon is the name both for the region and the only known city within that region.
In physics, a holon is an electron quasiparticle. This could be related to the electron storms in depictions of the region.