All you need is a card like Heartstone or Zirda, the Dawnwaker to reduce the cost of Sliver Queens effect, then cards like Earthcraft or Gemhide Sliver + a haste enabler, and you have access to infinite 1/1s
According to Sottosantis article, the team actually developed the purple concept quite a lot
Commissar Severina Raine and Elas il-Kor, Sadistic Pilgrim benefit you when you have lots of tokens
Still, it will be hard to justify trading the Shining Revelry promo, a shiny Mewtwo Ex, considering it can only be purchased with real money - an inevitable feature considering the game's gacha model
Power Card Show 5-9 | Treasure
Trainer cards also give you the opportunity to synergize and combo effects with your Pokmon attacks and abilities, letting you get more done on your turn than your opponent