Is there a reason to do the Zygarde anomaly battle?

[Racermannen]

I'm at the optional Zygarde Complete anomaly battle, and I'm wondering if I gain something from doing it instead of just obtaining the Zygarde without the battle,

[Green Bean 501]

It's not optional, you will need 100% Zygarde to complete the Xerneas and Yveltal quests

[Dry Ham]

From what I remember from my playthroughs, it's optional on the Lin route but compulsory on the Anna route. There's no point in doing it on the Lin route unless you want to.