Lore update: In Pokemon Emerald, Zexy the Torchic was lost through the PC after countless attempt at evolution, and hearts broke everywhere. Just hours before that, Nincada evolved into Ninjask on the first try, and with it came Shedinja, an animated hollow shell that is said to be able to capture spirits (Pokedex entry). It was then proclaimed that Zexy's soul would live on in the shell of Shedinja.
You know, at this point a novelization of the chronicles of Twitch Plays Pokemon is almost inevitable.