If you want to use physics for movement, use it exclusively.
Solid platforms would be set to immovable. You'll need to recreate all the other features of the platformer behavior yourself.
That said, there's nothing about portals that should need the physics behavior, given that portals are by nature NOT following physics rules, and the physics behavior is doing it's best to simulate real physics. Your decision to rely on physics is probably based on a flawed assumption to begin with.