The Pokémon TCG: EX Deoxys expansion was released on February 14th, 2005.

EX Deoxys

Have you taken a look at the EX Deoxys expansion yet? EX Deoxys adds multiple versions of the newly revealed Pokémon Deoxys and of the mighty Rayquaza. It also features stronger, hardier versions of previously released Pokémon, like Salamence ex and Crobat ex. There are new Poké-Powers and attacks that provide and manipulate Energy, and the new Trainer cards can radically alter players' tactics!

Deoxys
Deoxys is a newly discovered Pokémon that mutated from a space virus. There are standard and Pokémon-ex versions of Deoxys. Deoxys and Deoxys ex have the ability to shapeshift into three forms: Normal, Attack, and Defense. When Deoxys or Deoxys ex uses its Form Change Poké-Power, you can swap your current Deoxys or Deoxys ex card with another that is in your deck. Deoxys cannot shapeshift into Deoxys ex, or vice versa.

Rayquaza
There are three versions of Rayquaza in EX Deoxys: Rayquaza (22/107), Rayquaza ex (102/107), and Rayquaza (107/107). Each of these Rayquaza has a unique specialty.

Draw and Search
As you can expect with each expansion, EX Deoxys features new ways to draw cards and search for specific cards.

Professor Cozmo's Discovery (90/107) is a great new way to draw cards from your deck. Unlike most "draw cards," Professor Cozmo's Discovery doesn't require you to discard anything or have any limits on the size of your hand. All you have to do is flip a coin. Magcargo (20/107) works very well with Professor Cozmo's Discovery and Ludicolo (10/107), as well as any other card that helps you draw cards. Magcargo's Smooth Over Poké-Power lets you search for any card in your deck and put it on top of your deck. Combined with Ludicolo, you can draw that card after searching for it!

Are your opponents drawing a lot of cards? Not only can Mightyena (12/107) help you search for the cards you need, but it can also help you get rid of your opponent's cards! Its Seek Out attack lets you search your card for a single card and put it into your hand, and its Pull Away attack forces your opponent to discard cards until he or she has four cards left.

New Trainers
Balloon Berry (84/107) isn't exactly a new card, but a re-release. This version's text has been revised. Balloon Berry explicitly reduces the Retreat Cost to zero of the Pokémon that it is attached to. One big benefit of this is that cards like Dark Ariados (EX Team Rocket Returns, 30/109), Girafarig (EX Dragon, 16/97), Dark Muk (EX Team Rocket Returns, 16/109), and Muk ex (EX Dragon, 96/97), whose attacks are based on Retreat Cost, are weakened. It also cancels out any Trainer effects, attacks, Poké-Bodies, or Poké-Powers that increase Retreat Cost, such as Team Aqua's Hideout (EX Team Magma vs Team Aqua, 78/95) or Dark Muk's Sticky Goo.

Crystal Shard (85/107) is another re-release that will be very useful for countering strong Pokémon that are weak to Colorless-type Pokémon, such as Rayquaza ex or Salamence ex (103/107). Crystal Shard changes a Pokémon's type to Colorless when Crystal Shard is attached to it. Crystal Shard is also useful if the opposing Pokémon has a Resistance to your Pokémon's usual type. For example, Breloom (3/107) could attack Crobat ex for full damage if Crystal Shard was attached, because Crobat ex's Resistance to Fighting-type Pokémon would not be triggered: Breloom would be a Colorless-type Pokémon when it attacks.

Meteor Falls (89/107) is a new Stadium card that allows both players' Evolved Pokémon (except Pokémon-ex) to use attacks from their previous forms of evolution. This ability opens up many new tactics for the game. For example, Butterfree can continue to use Caterpie's (EX FireRed & LeafGreen, 56/112) Signs of Evolution to take Metapod (EX FireRed & LeafGreen, 39/112) and Butterfree cards from your deck so you can evolve a Benched Caterpie. Slaking (15, EX Ruby & Sapphire, 12/109) can use Slakoth's (73/107) Flail or Vigoroth's (EX Ruby & Sapphire, 47/109) Rage to cause a lot of damage if Slaking has damage counters on it. With Meteor Falls, there are countless strategies you can use to surprise your opponent.

Space Center (91/109) is another new Stadium card that turns off the Poké-Bodies for all Basic Pokémon (except Pokémon-ex and Pokémon with an owner in its name). When Space Center is in play, you can bypass the defenses of many Pokémon. For example, you can ignore Rayquaza's Dragon Aura and give it a Special Condition, while Wobbuffet (EX Sandstorm, 26/100) will lose its Safeguard Poké-Body and become vulnerable to attacks from Pokémon-ex (unless it evolved from Wynaut (EX Sandstorm, 54/100), in which case, Wobbuffet would be an Evolved Pokémon).

Source: https://www.pokemon.com/us/pokemon-tcg/ex-deoxys