So, Meltan can be used in LGPE indicates that it is an exception to one-way transfer from GO to Let's GO unless the Special Pokémon marketed in a present box is a different one.
Also, if Meltan is a Generation 7 Mythical, I believe GameFreak is on the right steps to avoid data-mining:
- A: Pokémon do not get leaked like Generation 6: USUM introduced 4 species that belong to Alola's Dex, and 5 if Meltan is also a part of it with LGPE.
- B: It promotes an efficient strategy to make customers buy the upcoming games by introducing new Pokémon.
Part of me thinks Meltan fits Generation 7 with all the 'cute' Mythicals it introduced: Magearna and Marshadow. But, I'd want it badly to be the Generation 8's successor. I hope it doesn't fall the Squishy-syndrome as a part of the current generation and get the Zygarde-Complete treatment in the next.