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What's the best nature for Mixed Autotomize Weakness Policy Aegislash, Naive or Rash? (Moveset in question would be Autotomize/Shadow Ball/Sacred Sword/HP Ice)
From what I understand every outcome (besides non-Masuda shinyness) is determined as soon as you reject/accept the the egg so the ability is always locked.
Selyth it's because you aren't using a female magikarp with Rattled as a scout so there's no way of knowing what slot ability you'll get when you switch out the parents.