Ok, so Ame has shown to be quite insightful with aligning the pokemon to the habitats. It's safe to assume we will be going to Ametrine, a Mountain featuringa lot of water and an ice path. That said, here is a list of poemon that i believe could appear barring the "OP" pokes that would require events.
Cubchoo
Cryogonal
Tentacool (we are approaching the point in the game where we need useful pokes like Cruel, but they won't break the game)
remoraid
geodude/graveler (it is a freaking mountain)
Onix
Swinub/ Piloswine
Basculin
Snorunt
Mebbe slowpoke although i doubt it, as Slowbro may be a tad too powerful.... Fat bastard