Body riding spirit - communicate but no control

[Refplace]

Granted by Familiar can work but from your description the limitation should be a lot less since your Spirit Ally is far less vulnerable.

For the Possession thing you could try a limitation on Spirit Possession with an enhancement to protect against Exorcism. Parasitic has a nasty downside.

Another way though could be Permeation (Flesh) and I would add a new modifier.
Ride Along
You are able to yourself to whatever you use Permeation on so that you move along with it, however it moves. Your weight does not count as encumberance and this cannot be used as an attack or to cause harm, though you do count as touching for purposes of other abilites, either yours or the one your riding. +20%

[Not another shrubbery]

Originally Posted by Refplace

For the Possession thing you could try a limitation on Spirit Possession with an enhancement to protect against Exorcism.

Yeah, Possession really looks like the logical way to go. I think this might have come up before, although a quick search didn't turn it up. You'd want to borrow Sensory from Mind-Reading and turn it into the Sensory Only limitation. The usual value so derived (-80%) looks too generous a discount to me, though.