>>33685053Steelix is almost a given since USUM is apparently including the Mega lines (aside from starters and legendary Pokemon).
Huntail was included in the name of a move you can perform in Mantine Surfing along with Gorebyss, so maybe.
The other two aren't confirmed but their inclusion won't surprise me since Game Freak usually includes past gen regional birds/rodents in dex expansions.