x2Stellar ReignIf your opponent’s Active Pokémon is an evolved Pokémon, devolve it by putting all of the Evolution cards on it into your opponent's hand.
If I use Shining Jirachi's "Stellar Reign" attack against a Stage 2 Pokemon that evolved from a Stage 1 which was put directly into play via Pokemon Research Lab, would my opponent put both the Stage 1 & Stage 2 cards into their hand (since both cards are "evolution cards") or does the Stage 1 card remain in play (since you can't "devolve" into nothing)?
Since you can't devolve into nothing, the Stage 1 card would remain in play.
What happens if Shining Jirachi with Choice Band attached uses its "Stellar Reign" attack against an undamaged, evolved, Lucario GX with Focus Sash attached? Does Focus Sash save the Pokemon from a KO?
During the attack Stellar Reign would do 80 damage (10 for the attack plus 30 for the Choice Band, then times 2 for Weakness). Then the devolution part of Stellar Reign would return all Evolution cards to the opponent's hand. However, when KO's are checked the devolved Pokemon is not the same Pokemon that was attacked, so Focus Sash would not protect the newly devolved Pokemon. The original Pokemon took damage from the attack, and the lower Stage just happens to have enough damage on it for a KO.