Well there's 593 files in the game for pokemon that I can see, do you think it's done by national dex ID? Yamper's ID in the files is 907, but his galar dex No. is 046.
46 in hex is 2E, 907 in hex is 38B
Hmm I think 907 is entirely plausible given the total number of pokemon and variants including regional variants. I'd probably try that first.