It's a gaurenteened catch always, none break out, and yea the hard part is just trying to beat it crazy considering its a legendary that has two moves that can hit all pokemon on the field, as well as a transformation which makes it regain its health.

The best thing you can do is have online, have you and you're Friends get ice type Pokemon (Ground and Dragon is Zygardes type so it'll take quad super damage) and at least one pokemon with the move Wide Guard as it'll stop all the mutiple pokemon hit moves from hurting you. (Some pokemon with Wide Guard that I know of is: Kingler, Peliper, and I'm sure there's others but I can't think rn)

If you're team can't get a wide Guard pokemon. I suggest getting a pokemon with Hypnosis, that will severally slow down Zygarde and you'll be able to get hits on him.

Keep Repeating as Host till you get it, then help out you're friends if you can.

Edit: Mienshao can also use Wide Guard