When is the IV/Nature/Gender/Shininess of a Gen 3 Starter determined?

Question

is it when you open the bag? when you press yes? or when the battle music plays?

dont question my curiousity.

Comments

I'm gonna question your curiosity.

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ive done 1542 resets today alone for a shiny mudkip and im just wondering

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I'm gonna question your curiosity. - PKThunder10

Same

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I'm pretty sure it's when you begin the battle with the poochyena.

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Not a full answer, but https://www.smogon.com/ingame/rng/emerald_rng_part2

Answer 1

Treecko/Torchic/Mudkip
Save in front of Professor Birch's bag. Spread selected after selecting "YES" on the screen that says "Do you choose this POKéMON?"

source