Its difficult to identify just one thing
It was wild
In no particular order, here is what I would consider meta decks: Regidrago VSTAR Toolbox (usually with Garbodor) Lugia VSTAR / Archeops with Double Dragon Energy Palkia VSTAR Shadow Rider Calyrex VMAX Stall, usually focused on Wobbuffet [Phantom Forces] or Snorlax [Pokmon Go] Fusion Strike decks, either focused on Mew VMAX, or Turbo Meloetta (with Dimension Valley) Of course, you then have other archetypes like Lighting stuff, Dark stuff, Arceus & Dialga & Palkia-GX / Dragonite V, Tsareena V, etc
Artists were selected on their capacity to deliver on one or all of the four parameters I set for the sets visual direction: Epic (scale and scope), Legendary (attention to lore), Storytelling (attention to characters and their relationships), Pastoral (what our heroes are fighting to protect)
Its been reprinted or functionally reprinted an absurd number of times and its original flavor text is absolutely iconic