"I can fix this,"Dialga said, filling them both with excitement, "I am the god of time, I can bring back Gardevoir, and revert her to how she was before the incident, though the memories will still be present, as had the man who caused this succeded in his attempt, we might all be destroyed, as this town was built over a special landmark, marking by power, and had that been exposed to the dark energy, I would have died as well, resulting in the end of the world." Dialga began to glow, and both Gengar and Gallade passed out. They awoke back in their new(or old) house, but with something in the hands of Gengar, one of the magic balls.
"He gave it to you, because you need to prove yourself in one final test." Gallade said.
Gengar opened the ball, and Gardevoir emerged, as herself once more. This is where one would say 'they all live happily ever after,' had that town not been in Japan, and had it not been during WWII, and had it not been destroyed by a nuclear bomb three days later. So yeah, no matter what, it's always a tragic ending... lol. I don't mean lol that Japan was bombed, just the irony of what happend, but I think they probably enjoyed the afterlife, especially Gengar, for whom it was really no different than geing alive.