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.

Relevant cards

SM11_205