I did a few transfers back when that was the way to get Meltan boxes, but it's been a very long time, and I was transferring random Pokémon that I would otherwise have sent to the Professor, not those that I have some emotional attachment to.
(IIRC, all IVs re-roll on transfer, if only because the mainline games have a different IV system than GO. Not all GO Pokémon, at this time, can be moved from Home to existing mainline games, though they can all move from GO to Home, and the new battle game just announced this week does specifically advertise itself as receiving from GO. Finally, there is no reverse -- it's a one-way trip out of GO into the mainline ecosystem, whether through Home or through the Let's Go games.)
from GO to Home
I did a few transfers back when that was the way to get Meltan boxes, but it's been a very long time, and I was transferring random Pokémon that I would otherwise have sent to the Professor, not those that I have some emotional attachment to.
(IIRC, all IVs re-roll on transfer, if only because the mainline games have a different IV system than GO. Not all GO Pokémon, at this time, can be moved from Home to existing mainline games, though they can all move from GO to Home, and the new battle game just announced this week does specifically advertise itself as receiving from GO. Finally, there is no reverse -- it's a one-way trip out of GO into the mainline ecosystem, whether through Home or through the Let's Go games.)