There's not an ounce of hesitation on Rei's end. She stops what she'd been doing (Standing around in shock), and calls her Gardevoir back.

"This is not good. We really cannot stay here. Harry-san, come! Now!"

And like or or not, Deimos has plenty of other ideas. Like getting out of here with everyone. The Pokemon shimmers and glows, exploding in a shower of light as it Mega-Evolves. The air around her shimmers, and in a flash Rei (and Harry if he's near enough) and several of the Gigan soldiers are just...gone. Safely away, thanks to a timely Teleport. Thanks for the obvious advice, Michiru!