Professor Oak caught Rotom in To Catch a Rotom! at Torom Island. He came to meet Ash and his friends to the Decolore Islands on Torom Island and told them that he wanted to catch himself a Rotom in order to study its forms. They went to a site where lots of old electrical machines were kept, luring in three Rotom. At first, Professor Oak's attempt to catch one failed. However, once he, Ash, and the latter's friends saved the Rotom from being captured by Team Rocket, one of them freely decided to come with him, and allowed itself to be caught by him.
Rotom reappeared in Butterfree and Me!, where it surprised Ash on the computer screen when he was contacting Professor Oak. Rotom was shown to be very affectionate towards him as it shocked him the first time it happened.
It appeared briefly in The Dream Continues!, where it suddenly popped down from the sky between Alexa and Professor Oak, scaring her. It was later seen being filmed by her.
Rotom is a mischievous prankster. A running gag, somewhat similar to the one with Ash's Muk, is that it often likes to fill up the screen whenever it appears and laughs. Whenever Ash has phoned Professor Oak since its capture, Rotom will appear first on the monitor, often scaring him. This habit has also been shown during Professor Oak's Holo Caster, where the segment will always begin and conclude this way. Rotom also likes using Thunderbolt to shock Professor Oak and laughs afterwards, though it doesn't seem to be using the move's full power, and doesn't want to really hurt the Professor.
From August 10 to September 6, 2013, Japanese Pokémon Centers distributed an in-game representation of Professor Oak's Rotom. The distribution was split into four one-week periods; each week, players could receive one of four Best Wishes-themed Pokémon at random. The other three Pokémon distributed alongside Professor Oak's Rotom were Ash's Pikachu, Iris's Axew and Cilan's Pansage.