How do you get the Rotom that can learn Hydro Pump?

Question

Can you get it on heartgold or any pokemon version

Answer 1

You get it in Platinum as an event Pokemon called Wash Rotom. However, in HG/SS, if you have a Rotom on your team, go to the Silph Co Building. You can now go up the elevator into a room. There are things here that will transform your Rotom into any of its different forms. You can come back here as may times as you want. Wash Rotom is the one that learns Hydro Pump.

Comments

Note: If you change Rotom's form from Wash Rotom, you will lose Hydro Pump. This applies to the moves specific to all the Rotom forms.