The Pokémon TCG: EX Holon Phantoms expansion was released on May 3rd, 2006.
EX Holon Phantoms
In the EX Holon Phantoms expansion, explorers and trainers search deeper in the forest near the research village of Holon, locating even more Delta Species Pokémon. Find your way through the dense foliage, and discover this expansion for yourself!
Trainers, Delta Species Style
Delta Species Pokémon get a strong boost from specialized Trainer cards in this set. Holon Adventurer (85/110) allows you to draw 4 cards instead of 3 when you discard a Delta Species Pokémon from your hand as part of the card's cost. Holon Lake (87/110) is a perfect setup Stadium card—Delta Species Pokémon can use Holon Lake's Delta Call attack to search your deck for their friends... Basic Pokémon or Evolution cards!
Fine Fossil Fashion
In this expansion, we learn that even Pokémon that come from fossils have been affected! Armaldo (1/110) expands its attack when discarding a Fossil card from your hand, hitting the Defending Pokémon and one of your opponent's Benched Pokémon. Kabutops (9/110) has a self-healing attack when it Knocks Out a Pokémon, as well as a Thunderous Blow that grows larger with each Lightning Energy on Kabutops. To make Fossil decks work even better, Holon Fossil (86/110) has the chance to grab the Evolutions from Fossils and put them directly into play... or just put them into play from your hand.
Bolstering Brawn Backup
The Pokémon in this set aren't just for frontline battling—Pidgeot (14/110) can shut down non-Delta Species Poké-Powers while a Holon Energy card is attached to it. Rayquaza (16/110) has the Hydro Barrier Poké-Body, removing Weaknesses on all of your Water-type Pokémon. Have a helpful Stadium card in play? Keep it around with Golduck (43/110), which has the Delta Block Poké-Body—your opponent can't play Stadium cards, at least not while you have a Stadium card with Holon in its name!
Energize Your Allies
Flygon (7/110) lets you add extra Energy cards each turn to Delta Species Pokémon... and who doesn't like that? Gyarados (8/110) boosts the damage output of your Delta Species Pokémon while a Holon-named Stadium card is in play. Perhaps strongest of all is Holon's Castform (44/110). Just like other special Holon Pokémon, it can be attached as an Energy card. But it's a Basic Pokémon that can be attached for two Energy, providing all types at once! Castform's attack isn't shabby either: for the attack cost of a single Energy of any type, you draw cards up to the number of your Delta Species Pokémon in play. Like so many of the great cards in EX Holon Phantoms, it's bound to reward you when you catch 'em all!
Source:
https://www.pokemon.com/us/pokemon-tcg/ex-holon-phantoms