This Rotom Phone was an electronic phone developed for Pokémon of the Rotom species to inhabit due to their special ability to take control of machinery. It was later given to Pokémon Trainer Ash Ketchum to serve as a guide and a Rotom belonging to Professor Cerise was chosen to inhabit it.
When Ash entered the World Coronation Series, Ash use his Rotom Phone to find other competitors to challenges them in official battles. After the battles, Ash check up on his ranks on his phone to see whether he rise up and move his rankings while trying to work his through all the classes to battle the Pokémon Champion of Galar and "Monarch" Leon.
None of Rotom's moves are known.
At Oak's Lab
At Kukui's house
At Cerise Laboratory