Decklist from Kanten.

Additional reading from LittleRiver (for Rayquaza ex δ/Camerupt builds).

Overview

This deck takes a patient approach to winning the game. Its main attacker is Marowak δ, a fairly ordinary-looking 80 HP Stage 1 with a spread damage attack in Energy Bone. Alongside various cards that disrupt the opponent, it uses Energy Bone to build up damage on the opponent's board. It can comfortably play while down Prizes, keeping Pow and Scramble Energy live, until one good Energy Bone seals the game by taking out enough of the opponent's Pokémon and Energy cards at once that they have no hope of making a comeback.

Ideal Gameplan

Lead with Stantler and use Push Away and Energy Removal 2 to strip the opponent's resources. Putting a Cessation Crystal on Stantler is also encouraged, as it can stop setup Powers like Jirachi's Wishing Star or Pidgeot's Quick Search. In the meantime, build Marowak δ(s) on your Bench.

Once the first Stantler is KOed and you're down Prizes, the fun begins. Use Pow! Hand Extension and Team Aqua Hideout to trap something vulnerable Active, and Marowak δ's Energy Bone to snipe their Bench. Scramble Energy should also be live, simultaneously providing the hard-to-fulfill {M} requirement on Energy Bone, and letting you Bone 2 more Pokémon. Refrain from taking Prizes as long as you can in order to extract maximum value from Pow and Scramble.

If you've trapped a vulnerable Pokémon Active on your opponent's side and have Minun Active on your own, you can utilize another winning strategy, which is spamming Sniff Out on Energy Removal 2 or Pow to deplete the opponent's Energy.

If you're going to fall back to being even in Prizes with your opponent, you can repeat the early-game strategy of annoying them with Stantler's Push Away until you're down Prizes again. Alternatively, you can send in Minun as a sacrifice, Sniffing Out as many cards as you can before it gets KOed.

Pay attention to the number of "answer" cards in your opponent's discard pile. Your disruption cards are Pow, Cessation Crystal, and Team Aqua Hideout, and their answers are switch cards (e.g. Warp Point/Warp Energy), forced switch cards (e.g. Warp Point again), Windstorm, and other Stadiums. If you know the typical number of answer cards that your opponent plays and realize all those answers are in their discard pile, it's a strong signal that you can lean in on one particular disruptive piece to take over the game.

Unique Points

This deck uses the Castaway toolbox. Energy and Cessation Crystals are things that you want on your Pokémon fast. Or, if you start with the wrong Pokémon, you can use Fluffy Berry to get it out of the Active Spot quickly. As Push Away costs 2 Energy, and this deck only has 11 Energy that Stantler can use, it's common to Castaway for another Castaway so you don't miss your second Energy drop. If you don't need more Energy, you can Castaway for Lanette's Net Search/Pokémon Fan Club to find Basics, or Holon Researcher to find Marowak δ.

Speaking of Holon Researcher, yes, this deck runs it without Holon Transceiver or the rest of the Holon Engine. It can search for either Marowak δ or Metal Energy.

With Marowak δ's Energy Bone, you can choose fewer Pokémon than it has attached Energy if you wish (for example, if you want to avoid taking a KO and turning off Pow/Scramble). You can't choose the same Pokémon twice.

This deck has the full 4 Pow and 4 Energy Removal 2 to screw with the opponent's Energy. Minun is especially deadly with these cards, as it can recur them.

A tip against Bombtar that's using Holon Energy FF to remove its Fighting Weakness: you can Pow Energy away to expose its Weakness again.

Tweaks

Unown E: Forces the opponent to put down Pow targets.

Rocket's Wobbuffet: Minun alternative. Recycles Pow, the usual Sniff Out target. Has 10 more HP and survives two 30 damage Fighting attacks.

Scott: To win Stadium wars. Can also act as a 5th setup Supporter, searching out Lanette/Fan Club/Researcher.

Cursed Stone: Alternative Stadium, might help with the low damage output.

The core of this deck (Stantler + Castaway toolbox + Pow + ER2 + spread damage attacker) is present in two other popular decks, each using Camerupt or Rayquaza ex δ as the attacker. You could consider these as alternatives to Marowak δ. A list of their pros and cons (thanks again to Kanten):

Rayquaza ex δ

Pros:

• Is a Basic, thus saving deck slots on Evolutions and Evolution searchers.

• Highest unconditional single-target damage (70).

• Highest HP (110).

• No Weakness.

• 1HKOs (Active) Pidgeot, leaves Jirachi at 10 HP with Special Circuit.

Cons:

• Can't use Cessation Crystal or Fluffy Berry, as it's an ex. Has to use Balloon Berry.

• Gets chipped by Desert Ruins.

• Gives up two Prizes when KOed.

• Low damage (30) if the target has no Powers/Bodies.

• Vulnerable to Latios ex δ (can't be Confused by Stantler, and immune to Rayquaza ex δ after it uses Ice Barrier), Safeguard Pokémon, and Mark of Antiquity Groudon ex.

• Same type as Minun, so Lanette's Net Search can't get Rayquaza ex δ + Minun.

Camerupt

Pros:

• Has good attacks other than the spread damage one: Numel's Kindle discards Energy, Camerupt's Back Burner gets it back.

• Decent overall damage (30*2 for 3 Energy).

• Can use Cessation Crystal, Fluffy Berry, and Heal Energy.

• 1HKOs (Active) Jirachi with Split Bomb.

Cons:

• Weak to Mew ☆ δ, and can have Back Burner copied to undo its disruption.

Marowak δ

Pros:

• Cubone has a setup attack.

• Highest overall damage under ideal circumstances (20*6, or 90), decent overall damage (20*3 for 3 Energy).

• Can use Cessation Crystal, Fluffy Berry, Metal Energy, and Scramble Energy. Metal Energy is particularly useful against opposing spread damage attacks, and lets you survive 40 damage Grass-type attacks (e.g. Dragonite ex δ's Deafen) from full HP.

• Lowest Retreat Cost (1).

• Hits Dark Tyranitar and Stantler for Weakness.

Cons:

• Low damage to individual Pokémon (20). Takes more turns to bring one troublesome Benched Pokémon down to 0 HP.

• Requires 2 types of Energy for Energy Bone, one of which is Metal (non-basic). Vulnerable to getting color screwed by Crystal Beach (if using Scramble Energy), Energy Removal 2, or Pow. Also can't use Mr. Stone's Project to get those Energy back from the discard; the only way to get back Special Energy is Minun's Sniff Out.

• Less Energy compatible with Stantler, as it can't use Scramble Energy.

• Resisted by Pidgeot.

Strengths

(Some strengths and weaknesses have already been covered in the previous section.)

This deck has many ways to restrict the opponent. Energy Removal 2 and Pow mess with their Energy, Push Away discards their Trainers, Cessation Crystal stops Powers/Bodies, and Team Aqua Hideout + Pow traps vulnerable Pokémon.

This deck is very good at playing from behind, thanks to Pow and Scramble Energy. These cards enable amazing comebacks from seemingly hopeless positions.

Weaknesses

This deck's damage output is not high. Usually, you win because your disruption causes your opponent to be unable to attack, so while your damage output is low, theirs is even lower (0, or even negative if they get Confused by Stantler and lose the flip). If your opponent can overcome that disruption and attack normally, you are probably not winning the resulting contest of strength.

Warp Energy counters multiple angles of attack from this deck. It switches out anything that's been Pow-ed Active, cures Confusion from Screechy Voice, and can't be discarded by Push Away. Other switch cards are also good, but vulnerable to Push Away.

Trainer locks (e.g. Manectric ex, Dragonite ex δ) prevent this deck from playing its disruptive cards: ER2, Pow, Cessation Crystal, Team Aqua Hideout. You need to buy turns against them using Stantler's Screechy Voice and hoping they flip tails.

Holon Farmer can get Energy (including Holon's Pokémon) back from the discard, undoing all the work that ER2 did. Push Away is not a hard counter to that, as decks playing Holon Farmer will have Holon Transceiver to recover Farmer if it's discarded. Other cards that can get Energy back (e.g. Kingdra ex δ, Raticate) are also effective, more so if they're on attacks instead of Poké-Powers, as Cessation Crystal shuts the latter down.