How does the rotom forms work?

Im talking about gen 4 and I know you can change rotom forms in one of the D/P/Pt games and Hg/SS. But once you change its forms to lets say the heat one which is fire/electric typing. Then does it get stab on ghost attacks at all? And can you change its forms back to the original one once you’ve changed it? Also is it kind of like an arceus where you can just change the forms depending on your moodI really dont understand how the forms work and I looked it up on google but I still dont understand it so can someone explain this to me in an easy way so I can understand?

Pleaselog inorregisterto add a comment.

In Generation IV, it was Electric/Ghostregardlessof its form.

Source:Bulbapedia

Yes, you change him back to his original form.

It’s only in Generation V that his type changes with his form.

When itdoes not possessan appliance, it is Normal Rotom, and isElectric/Ghost

When it possesses amicrowave ovenit becomes Heat Rotom, and isElectric/Fire

When it possesses awashing machineit becomes Wash Rotom, and isElectric/Water

When it possesses arefrigeratorit becomes Frost Rotom, and isElectric/Ice

When it possesses arotary fanit becomes Fan Rotom, and isElectric/Flying

When it possesses alawn mowerit becomes Mow Rotom, and isElectric/Grass