None of the cards themselves are super complicated, but simply playing the deck will give you a headache if you dont know what you are doing

Dark Sylveon V - SWSH134 #SWSH134Promo $4.91 Dark Sylveon V - SWSH134 #SWSH134Promo $6.92 Gardevoir & Sylveon GX #130Ultra Rare $77.29 Gardevoir & Sylveon GX - 031/055 #31Double Rare $32.58 Gardevoir & Sylveon GX - 060/055 #60Super Rare $55.00 Gardevoir & Sylveon GX - 061/055 #61Super Rare Gardevoir & Sylveon GX - 067/055 #67Hyper Rare $129.99 Gardevoir & Sylveon GX (204) (Full Art) #204Ultra Rare $104.00 Gardevoir & Sylveon GX (205) (Alternate Full Art) #205Ultra Rare $624.99 Gardevoir & Sylveon GX (Secret) #225Secret Rare $161.93 Sylveon Collection Furious Fists Theme Deck - "Enchanted Echo" [Sylveon] $350.00 Evolution Celebration Tin [Sylveon GX] $148.24 V Heroes Tin [Sylveon V] $114.49 V Heroes Tin [Sylveon V] (International Version) $73.24 Evolving Skies Elite Trainer Box [Glaceon/Vaporeon/Sylveon/Espeon] $522.91 Evolving Skies Pokemon Center Elite Trainer Box [Glaceon/Vaporeon/Sylveon/Espeon] (Exclusive) $1010.82 Evolving Skies Pokemon Center Elite Trainer Box Case [Glaceon/Vaporeon/Sylveon/Espeon] (Exclusive) Slowbro #49Uncommon $0.45 Politoed #25Holo Rare $2.33 Slowpoke #48Common $0.29 Litwick #11Common $0.19 Alolan Golem #42Holo Rare $0.57 Garbodor #51Rare $0.41 Gothitelle #54Rare $0.31 Alolan Graveler #41Uncommon $0.21 Trevenant #7Rare $0.29 Mimikyu #58Holo Rare $10.56

You can likely guess what fairy tale trope its referencing from the title, but to reinforce the hint it uses a new mechanic, bargain, which gives you a bonus effect if you sacrifice an artefact, token or enchantment
This is one of the biggest transitions for the Pokmon TCG meta in recent years, but its way overdue
Perhaps the exclusivity on the Galaxy foil just expired, and now WotC can use it on other products
And one of the most crucial is selecting the right card leading card