>>24984685That's fairly straightforward: Track down the individual parts before they fuse into the perfect form and murderhobo the fucking shit out of them.
The Zygotes are the easiest by a country mile, most Pokemon should do the trick, or a reasonably sturdy shovel. Ground type, so don't let it dig away either either and you're golden.
The Zydogs are much harder to pin down, probably being fast little shits and the start of the difficult fights, but very difficult to prevent. Bring your good game, and either something strong enough to obliterate it in one go or fast enough to cut off escapes, ideally both.
Do a bad enough job of keeping the Zydogs apart and you have to fight Zygardes, and pray you didn't leave enough of the others alive to make two. Bring your legendary level shit. Call in a favour from a champ like Blue or Cynthia even. Not Alder, though, he's fucking useless.
You've fucked up so bad they reached Zygod? Play dumb on the murder it plan, make up some retarded plea about how this coincidentally nearby, innocent orphan deserves a chance at life or whatever.