So yes which, if any, elementals do you allow skyward once materialized? Mainly this was for 3d game.

Is it all of them with 3d movement?
Some of them? Why?
Or none of them because gravity effects anything physical.

Personally, when this came up at our table I ruled ad hoc that earth and water where earth bound but fire and air could 'fly'.

Your personal preference answers on a post, please?

Selections of houserules from our game:

Air and Fire Elementals and Spirits of the Sky can fly, which allows them "higher ground" advantage in melee. Water and Earth elementals and Spirits of Man, Water and Land cannot fly, though Water elementals and Spirits of Water take no damage from falling. Flying has the same speed as normal movement.

I would rule that if something takes on a physical aspect then they should have some of the limitations and advantages of said aspect.

Keeping earth and water landlocked but giving them the ability to "fly" underground and underwater is a good exchange and also gives the elements distinct differences.