How do I get a wild Rotom in Pokemon Sun?

They will most likely paw at the area and hide until they are feeling better.

You have to proceed far enough into the story to get to Poni Island. From there, you have to enter the Steelix house and exit out the side door. There...

Have your starter evolved all the way, then breed with Ditto. Trade that starter for the other starters. Or go on GTS and trade whatever the other person wants so...

Go to Paniola Ranch or Route 4 and run in the grass for a while - you'll soon come across a cute little Eevee!

Ask a friend with Sun to evolve it for you.

Nope. Sorry, but most one-time Pokemon (such as Rotom, Heatran, and the Lake Guardians) will never show back up again if you accidentally knock them out. Newer games do address...

Yes. If you have a lot of time to spare and have quick hands, considering you'll have to do a lot of trying and reseting before catching one.

Yes. Until you receive the National Pokedex, you will not be able to encounter Rotom. This holds true for Pearl as well, but not for Platinum, where you can battle...

You can only obtain it via special event/mystery gift. However this game is no longer supported for events and thus Celebi is not obtainable without transferring it from an old...

You could either trade (using the GTS, online connection, or by asking a friend) or use the Pokébank to transfer it from another game.