For the non elemental allies I assume their basic punch is plain physical damage and would be increased by +%physical damage.
I was wondering for the fire and cold ally though if their base attack is their elemental type or if it's still physical?
I know their active ability is fire and cold damage, but wasn't sure about the basic attack.
I tried on the Convention of elements, and noticed the fire pet's attack damage goes way up when the fire element comes around. So yes, the basic attacks are also elemental based.
So in theory, with the new Inna's 6 pc and convention of elements, almost always a mystic ally is doing 200% more damage.