A petitioner is, essentially, the soul of a deceased character that has found its way to the plane to which it belongs. However, as far as I am aware, it does retain its level and abilities - at least to a degree.
What would happen if a petitioner is subjected to the Plane Shift or similar spell - either by its own casting or otherwise - and, through that manner, brought back to the Material Plane? What would its type and/or statistics be? Would this at all be possible?
And would there be any consequences beyond pure mechanics to the petitioner in question? Consequences for the plane of origin and the arrival plane, for example?