*The English set was released ''before'' [[EX Legend Maker (TCG)|
Eidolon Forest]] ( Eidolon Forest was before Research Tower of [[Holon]] in Japan), as there was a mix-up with translations. This once again threw the English sets out of sequence with the Japanese sets. Because of this, the English set was only a few days behind the release of the Japanese set. However, the Prereleases were held before the commercial release of the Japanese set, making this the first set in history to be revealed for the first time outside Japan.
*The set reveals the Holon Research Tower, located in the middle of [[
Eidolon Forest]] (already introduced in Japan; introduced in the next English set); it is the home of scientists who conduct research on Mew and strange new Pokémon. These Pokémon have been altered by a wave of electromagnetic radiation produced by an experiment gone awry at Holon labs. The result - δ Delta Species.
*These new Pokémon possess types different from their original and some, in their fully evolved forms, are partially [[Metal (TCG)|Metal]]-types. They could be considered as the counterpart to [[Dark Pokémon (TCG)|Dark Pokémon]] in the EX series.
*EX Delta Species also introduces Holon's Pokémon, which are unique as they can double as Special Energy cards, and new Trainer cards which centralise themselves around the Holon Tower community.