What causes the game to crash when Metronome calls certain moves in Sw/Sh?

Question

So, I have seen this in a metronome battle. Someone got Fairy Lock from Metronome, and the game crashed! Also, once I saw someone use Misty Terrian and the game still crashed! Could someone explain to me why this happens?

Comments

Can you please add a link to where you saw or read about this happening, for both of the moves you mentioned?

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Sure, right here: https://youtu.be/LWULmi-mcnU?t=925

If it doesn't automatically, go to 15:25

Answer 1

Easy answer:

Because no Pokemon able to learn fairy lock exists in Gen 8, the move crashes the game if animations are on (because while data exists for the move, its animation does not exist in SwSh version 1.1.0).

However that video was old and the problem was fixed in version 1.1.1. by adding more data to the move.

Misty terrain works fine.