What are all the three stage evolutions that don't require level up to evolve?

Question

Excluding Pokemon that evolve through happiness.

EDIT: I forgot to mention that the Pokemon have to be from stage one and evolve to stage three without leveling up at all. If there are no Pokemon like that, then you can answer with that. I'm sorry for any confusion caused.

Comments

But Eevee isn't a three stage evolution!

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Oops, my bad. Edited.

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I'm answering this, may take a while. editing my answer so much, so don't down-vote or  flag my answer yet, I'm editing please.

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You are editing so much, I have to edit MY answer so much ughh.
If you dare change it back, I'll hide my answer completely.

Answer 1

Just one(if I understand correctly. You mean like, you can get a final evo without leveling up at all from the unevolved Pokemon right)
The porygon line
Porygon->Porygon2 (Up-Grade)
Porygon2->Porygon-z(Dubious disc)

Sources:this,this, this, and experience,

Comments

Thank you.

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your welcome

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Yay the Porygon line. XD

Answer 2

Now that you've ruled out all except the first evolution, there is only one.

Pokemon that evolve while trading with an item:

Porygon (Pokémon)

Porygon evolves while trading with the Upgrade, and is the only first evolution to evolve while trading with an item.

Source, and remembering what I put in my answer to ~megaltaria~'s question

Hope I helped!

Comments

Oh yea, editing again...

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wut I added my porygon answer before youuuuuuu

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Yes, so? Sorry, I just remembered that Gloom wasn't first evo, and Absolover-*megaltaria told me.

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Thank you both.

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No problem! :)