RayEels is a Pokémon Trading Card Gamedeck archetype that was popularly played in the 2012-2013 season. The deck's strategy revolves around charging BenchedRayquaza-EX with Energy to power up its Dragon BurstAttack and Knock Out any opposing Pokémon in one attack. This deck was known for its straightforwardness and ease to play for beginner players. Rayquaza-EX was also one of the few Pokémon that could Knock Out virtually any Pokémon-EX in one attack without needing to hit for Weakness. RayEels ranked 2nd place in the Seniors Division at the 2013 Pokémon Trading Card Game World Championships but, despite struggling against decks with Garbodor, had better results in other events beforehand. Juniors Division runner-up Clément Lamberton's version was printed as a promotional World Championships deck, Anguille Sous Roche.
RayEels is similar to other decks that use Eelektrik's DynamotorAbility to charge Benched Pokémon with Energy from the discard pile. Rayquaza-EX takes advantage of this engine, as its attack discards these Energy cards, but unlike most other attackers in Eelektrik decks, it also needs at least one Energy attached to deal damage. Its Dragon Burst attack discards either all or Energy attached to it to deal 60 damage for each discarded card. With three Energy attached (plus one Energy for the attack's cost), Rayquaza-EX deals 180 damage, which was enough to Knock Out every Pokémon in the format.
The deck's goal is to have three to four Benched Eelektrik, one active Rayquaza-EX with enough Energy to attack and a Benched Rayquaza-EX to charge up with Dynamotor the next turn. Professor Juniper and Ultra Ball were crucial Trainers in the deck, since the player would ideally want as many Energy cards in the discard pile as possible within the first few turns. RayEels could also use many supporting attackers thanks to its use of multiple Energy types and its consistent Energy acceleration. Post-Boundaries Crossed, Keldeo-EX and Float Stone were common for easily retreating Pokémon without Energy.
Rayquaza-EX - Rayquaza-EX's Dragon Burst attack can consistently do good damage with the Dynamotor engine. Its Celestial Roar attack is another way to attach Energyto itself, but it comes with the risk of discarding valuable resources.
Eelektrik - Eelektrik's Dynamotor can attach a energy to Benched Pokémon, typically Rayquaza-EX. Eelektrik's Electric Ball attack can potentially Knock Out damaged Pokémon, but the deck usually prefers better secondary attackers.
Keldeo-EX - Keldeo-EX's Rush In Ability switches it into the Active Spot, allowing a Rayquaza-EX that had attacked the previous turn to be powered up again, while still letting the player retreat it afterwards.
Float Stone - Removes the Retreat Cost any Pokémon in the deck. This is best used on Keldeo-EX, as its Ability makes retreating with other Pokémon virtually unnecessary.
Super Rod - Super Rod recycles energy and often important Pokémon that end up discarded by Trainer cards or by being Knocked Out.
Ultra Ball - Ultra Ball can be used to discard Energy and search for any Pokémon in the deck.
Level Ball - Level Ball can easily let the player get Tynamo and Eelektrik from the deck without any drawbacks.
Skyarrow Bridge - Skyarrow Bridge allows Rayquaza-EX and other Basic Pokémon with only one retreat cost to freely retreat.
Professor Juniper - Professor Juniper can discard Energy and draw cards at the same time.
Typical decklist
Clément Lamberton's decklist at the 2013 World Championship
The following cards are often used in RayEels in place of certain cards included in the above lists.
Raikou-EX - Raikou-EX can deal 100 damage to a Benched Pokémon, sniping certain threats before they become a problem.
Mewtwo-EX - Mewtwo-EX is a cheap attacker that can use any type of Energy and offers coverage.
Zekrom - Single-prize attacker that deals decent damage. Could turn matches either favorably or unfavorably when starting the game in the Active Spot, since it has 130 Hit Points (which was a large number for a single-prize Basic Pokémon at the time), but cannot easily retreat.
Victini - Strong counter to Pokémon, Victini is a single-prize attacker that can deal 100 damage for 2 Energy.
Rayquaza - Rayquaza's Shred could damage Pokémon that are immune to Rayquaza-EX. Additionally, it can hit opposing Rayquaza-EX for Weakness.
Energy from the discard pile. Rayquaza-EX takes advantage of this engine, as its attack discards these Energy cards, but unlike most other attackers in Eelektrik decks, it also needs at least one 
Energy attached to deal damage. Its Dragon Burst attack discards either all 
retreat cost to freely retreat.
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coverage.
Pokémon, Victini is a single-prize attacker that can deal 100 damage for 2 Energy.