What if a Pokemon from a different generation has the same OT, ID, and SID as you?

Question

You have the same OT,ID and SID of a Pokémon recently traded to you, however that Pokémon originated in Sun and Moon and you are playing X/Y.

Comments

A Pokémon that originated in a Gen 7 game (like SM) cannot be transferred to Gen 6 (like XY).
However, discounting generational differences, the games also record the OT’s gender, and I believe which game version the Pokémon was originally caught in, as well. So if you have two games of the same version with (at least) the same OT name, OT gender, ID, SID, and (in Gen 7) TSV, then, in theory, a Pokémon caught in one game would not be recognized as an outsider Pokémon if traded to the other. It’s very possible that there are other factors that the game also checks for, though, and I have no way to test this, so this may not be a conclusive answer.

---

I have ways to transfer from Gen 7 to 6, but say it’s from 6 to 7.

---

If it’s from 6 to 7 then the game will absolutely recognize it as an outsider Pokémon. For one, IDs (and SIDs) in Gen 6 range from 00000-65535, whereas in Gen 7 it ranges from 000000-999999, so it’s actually impossible to get the same ID (even low numbers like 10000, for example, would be displayed as 010000 because of the extra digit) Plus, it’ll have the blue pentagon origin marking instead of a black cross.

Answer 1

Though from Gen 6 to 7 it would be impossible (since Trainer IDs were lengthened to six digits and secret IDs were shortened to four digits), I tested it in Pokémon Platinum with PKHeX and an overleveled Taillow from Emerald. Though the summary screen will say it arrived at a certain level (like any other Pal Park-obtained Pokémon), the game will recognize the Pokémon as yours.