Question

They both seem equally likely becuase it could be an electric controling it or a ghost possesing it

Answer 1

No, every Rotom is Ghost/Electric in Gen IV. But different formes can learn different moves:
Mow: Leaf Storm
Fan: Air Slash
Wash: Hydro Pump
Heat: Overheat
Frost: Blizzard

UPDATE: as of Generation V, Rotom changes type when its forme changes:
Mow: Electric/Grass
Fan: Electric/Flying
Wash: Electric/Water
Heat: Electric/Fire
Frost: Electric/Ice

Comments

That's totally not true. The Electric type stays, while the Ghost type changes, depending on the form of Rotom.

---

This was true at the time this question was asked, which was during Gen IV, before the change for Rotom in Gen V.

---

Answer edited.