"Bye!" Gardevoir called. He was cut off mid-word by his
teleportation, making it sound like "Ba-" to Yveltal and "-ie!" to
anyone on the southern island, which was the location to which he
had teleported.
(This is mostly irrelevant but interesting: weirdly, the games
don't say anything about the lives Yveltal absorbs actually making
a difference. I think they just absorb them for the purpose of
being destructive in their last moments, but die anyway.)
Suddenly, a swirl of green energy appeared around a certain point
of the ocean. This swirl of energy shot all the way into the sky as
a beam of light, and then disappeared, taking Zygarde with it.
At around the same time, a beam of green energy shot down from the
sky in the very center of the southern island. A huge wind pulsed
from it until it faded, revealing a fully formed but unconscious
Zygarde.
(Are you referring to the Cocoon of Destruction, Yveltal's form
when it is dead/near death?)
Gardevoir, having teleported to the southern island, was fairly
close to the beam of light. It seems even this island has its
mysteries, he thought before going over to investigate. He was
shocked when he saw Zygarde, the Legendary Order Pokémon. The green
serpent stirred.
(Both of my Pokémon are green and contain "garde" at some point in
their names. Prior to the introduction of Servine, both of your
Pokémon ended in L and had a shade of red somewhere on their
bodies.)
(Wait... now there's nobody but Excadrill on that island. XD Would
you like me to make a character to meet Excadrill?)
"A-are you t-the Legendary Zygarde?" Gardevoir asked.
Zygarde didn't move or say anything.
"HELLO? IS THERE ANYONE NEAR HERE? I THINK ZYGARDE NEEDS HELP!"
Gardevoir shouted.
(OH. Okay, then. In that case, I shall decide on something to be
corrupted later. ^^ Until then, how about having Servine hear
Gardevoir or just stumble upon the area? ^^)
"I think Zygarde is hurt," he said. "He isn't responding to me and
he isn't moving at all. He also seems to have either come out of
the sky or been attacked by a green beam of light from the sky,
neither of which is good."