yugioh stardust accelerator deck / Synchron from 𝓥𝓮𝓬𝓽𝓸𝓻 yugioh stardust accelerator deck Amazon.com:

Star Seraph Scale X LIGHT Level 4 [ FairyEffect ] ATK 1500 DEF 900 When this card is Special Summoned: You can Special Summon 1 "Star Seraph" monster from your hand, then you can place 1 LIGHT monster from your Graveyard on top of your Deck

Take control of Harpie Lady Sisters and attack directly with Wynn and Harpie Lady Sisters

A Single Japanese Card Only.

Basically, they sit outside the game (but not in a sideboard slot), get put into the Command Zone, and from there they generate effects

Cantrips become mana-neutral

For Sinnoh however, it was an anime original location and no where near where the Elite Four and Champion were fought in the games