Blastoise/Keldeo focused on playing Blastoise as soon it was possible to use its DelugeAbility, which similar to the first printed Blastoise allowed to play as many Energies from the player's hand to Pokémon in play during their turn. Keldeo-EX and Black Kyurem-EX (introduced a set later) were the most useful attackers for the deck, with the potential to knock out most Pokémon in their active formats with the right setup but the need to use many Energy cards. The deck used resources such as Rare Candy to speed up the Blastoise setup and Superior Energy Retrieval to not run out of Energies.
While not the most sucessful deck of the formats it was active, Blastoise/Keldeo was known for its straightforwardness and ease to play for casual players. The release of Primal Clash introduced Archie's Ace in the Hole, which mutated the archetype into Archie's Blastoise and allowed Blastoise to stay relevant in future formats.
Blastoise - The Deluge Ability allowed the player to attach as many Energies from their hand to Pokémon during their turn. As a Stage 2 Pokémon, it was important to have more than one line in play to avoid the impact of its knockout.
Keldeo-EX - Secret Sword scaled damage for each Energy attached to Keldeo; at 7 Energies, it could knock out any Basic Pokémon-EX (and non-EX Pokémon for less). Its Rush In Ability was also useful at easily becoming the Active Pokémon.
Black Kyurem-EX - Black Ballista allowed Black Kyurem-EX to knock out most Pokémon before the introduction of M Pokémon-EX, but forced Energy cards to be discarded and required a Energy.
Electrode - Used to draw cards each turn and prevent a resourceless hand from opposing players playing N.
Rare Candy - Skipped the middle evolutionary Stage for Blastoise, allowing its setup at the player's second turn.
Tropical Beach - Used to draw cards. Tropical Beach's drawback of ending the turn with its effect was not harmful in the first turn, since the player could not use any expensive attack. Notably the most expensive card in the Standard Format while it was in rotation due to its low distribution.
Typical decklist
Alex Croxton's decklist at the 2014 World Championship ]
The following cards were often used in Blastoise/Keldeo in place of certain cards included in the above lists.
Suicune - Secondary attacker that was immune to damage from Pokémon-EX. It did not deal too much damage compared to the main attackers, though, and Blastoise itself could act as a non-EX attacker.
Mewtwo-EX - Cheap attacker against Pokémon such as itself or Garbodor.
See Also
Archie's Blastoise
This article is part of Project TCG, a Bulbapedia project that aims to report on every aspect of the Pokémon Trading Card Game.
Energies from the player's hand to Pokémon in play during their turn. Keldeo-EX and Black Kyurem-EX (introduced a set later) were the most useful attackers for the deck, with the potential to knock out most Pokémon in their active formats with the right setup but the need to use many Energy cards. The deck used resources such as Rare Candy to speed up the Blastoise setup and Superior Energy Retrieval to not run out of Energies.
Energy.
Pokémon such as itself or Garbodor.