Why is Phione before Manaphy in the Pokedex?

Question

Phione hatches from an egg from Manaphy, but is first in the pokedex, why is that?

Answer 1

Because every mon that hatches from an egg is before the parent except for certain situations meaning like mime jr, Bonsly, happiny who come in later generation. If you breed a charizard you get a charmander which is before charizard

Comments

That makes sense.
Thanks!

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@Hellfire Taco
You just forgot the most important thing. Phione doesn't evolve into Manaphy, unlike Charmander does into Charmeleon, so your answer is wrong. There is no exact answer

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Can you elaborate on how that makes this answer wrong? When did a Pokemon have to follow this rule about evolution, and how does that make this breeding argument incorrect? I'm not disagreeing there is no "exact" answer, but I'm not following your logic either.
Also, I think you're addressing the wrong person. Hellfire Taco asked this question to begin with.