Can you battle Necrozma again in US/UM if you knock it out?

Question

In Pokemon Ultra Sun, I accidentally knocked Necrozma out. Where would I get it again?

Comments

If you haven't saved yet, you can soft reset your game to the point where you last saved. But if you did save already, you have to resort to the GTS for your Necrozma.

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You might be able to battle it again if you defeat the Pokemon League.

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use a quickball its new catch rate is 255 or 33.3%, making it as easy to catch as a ratatta

Answer 1

Assuming you mean when you encounter it at Mount Lanakila right before the Pokémon League (where you actually have a chance to catch it), YES. Just become champion/defeat the League again and it will be waiting in exactly the same location.

Source: experience.

Answer 2

Yes you have to become champion and defeat the league again and Necrozma will be in the same crater where you found it. I highly reccomend to save the game before battling Necrozma, so if you knock it out again, you can just try again from where you saved.