What are the rarest Pokémon you can have in Gen 8?

[Guest]

Are there certain Pokémon that you could only get in Pokémon Go with certain moves and transfer them to Gen 8?

 

Or what about Pokémon like that limited Hydro Pump Drillbur that wasn’t meant to be released?
 

Just looking for Pokémon that are the rarest to have. 

[ShadyGabe]

I'm not sure which one would be the rarest, but I can say one of them can be the G-Max Hattrem from about a month ago.

[theSLAYER]

20 minutes ago, PkHexBoi said:

Are there certain Pokémon that you could only get in Pokémon Go with certain moves and transfer them to Gen 8?

For almost all mons, no, not really.

If in LGPE => Get LGPE level up moveset
Else in SWSH (but not in LGPE) -> Get SWSH Level up moveset
Finally, if in USUM (but not in LGPE nor SWSH) -> Get USUM level up moveset

The only exceptions are Pokemon that have their main form in LGPE that are also regional variants
(Like Alolan Vulpix, Galarian Ponyta)
There was a glitch where those mons would instead get the level up movesets from their main forms.
However, an invasive Pokemon HOME update fixed those moves (in HOME, in your save, in your daycare, in your pokejobs, all fixed).

However, that update did create some oddities with certain moves. (something about learning TR moves without TR flag I think?).
But anyhow, it's all moves a mon could learn.

So no unique moves from GO.

(Also, Pokemon transferred from GO don't retain their GO moveset, if the above portion ain't obvious enough >< )

20 minutes ago, PkHexBoi said:

Just looking for Pokémon that are the rarest to have. 

Gen 3 Japanese Shiny Mew obtained via the real life event, by yourself, without hacking nor injecting.