Trevenant BREAK differed from archetypes such as Mega Rayquaza EX and Night March in that it did not focus on fast first turn set up to maximize the damage output, because Trevenant BREAK was an evolution with a spreading damage that, after many attacks, should knocked out all big Pokémon at once. This early disadvantage was compensated by the XY Trevenant's Forest's Curse Ability preventing the opponent from playing Item cards and Trevenant BREAK's Silent FearAttack placing 3 damage counters on each opposing Pokémon, putting up to 18 damage counters per turn. As a Pokémon BREAK, Trevenant BREAK also had the Ability and Attacks of its pre-evolution, allowing it to slow down the opponent with Forest's Curse while flooding the board with damage counters.
Some important cards allowed the Trevenant BREAK deck to not fall behind the opponent's pace. Phantump's Ascension Attack and Wally allowed Trevenant to be put in play quickly and ensure the opponent would be always Item-locked after the player's first turn. Dimension Valley reduced the Attack cost of Silent Fear, allowing many single-energy attacks during the game. Rescue Scarf also put knocked out Pokémon back to the player's hand and allowed the main attackers to be constantly put back into play.
Trevenant BREAK had some serious trouble against decks due to the type disadvantage and decks with Hex Maniac (which was later banned), but was a popular choice by its matchup against more popular archetypes.
Trevenant BREAK - Trevenant BREAK's Silent Fear Attack put 3 damage counters on each opposing Pokémon in play, knocking out without other modifiers Night March Pokémon in at least two attacks, Shaymin-EX in four attacks and other Basic Pokémon-EX in six attacks. With 50 more Hit Points than its pre-evolution, it could survive attacks Trevenant otherwise wouldn't.
Trevenant - Trevenant's Ability locked the opponent out of playing Item cards while it stayed in the active position. Because of that, the deck only used other attackers near the game's end to maintain the Item lock. Its Tree Slam attack was an option to Trevenant BREAK knock out the active Pokémon faster than by spreading damage, but needed one more energy to use.
Phantump - Its Ascension Attack was useful at placing Trevenant on the field as quickly possible and reducing the need of Pokémon-searching cards.
Tapu Lele - A late but great addition that moved damage counters between opposing Pokémon and ended the game earlier by knocking them out.
Rescue Scarf - In the Expanded format, it retrieved knocked out Trevenant back to the player's hand and was the most played Tool card for this deck. Rescue Scarf did not work by knockouts from effects of attacks.
Dimension Valley - Thanks to Dimension Valley, the player could use Pokémon's Attacks for one less energy and prevent turns without any damage placement.
Wally - Wally sped up Trevenant's evolutionary stage and, if played on the first turn, guaranteed the opponent out of Item cards for most or all their game. The Wally/Trevenant combination was so strong it led this card to be banned later from the Expanded format.
Enhanced Hammer - Additional stalling to prevent the opponent from getting to attack. The deck would often use other energy dirsruption cards.
Red Card - Along with N, Red Card reduced the chances the opponent would have a Supporter card or Shaymin-EX in their hand to get the needed cards despite the Item lock. A combo with Delinquent also kept the opponent's hand at one card to further disrupt their pace.
Riku Ushirosako's decklist at the 2016 World Championship
Head Ringer - Countered Pokémon-EX by increasing their Attack costs.
Mystery Energy - Allowed Trevenant to retreat easier but, despite the Item lock preventing the opponent from discarding this energy with Enhanced Hammer, it was vulnerable to Supporter cards that removed special energies.