Disclaimer: I wouldn't write this if I did own it. I would put it on TV instead
Narrator's POV
"Come on Giratina, let's play!" four year Harmony yelled cheerfully, as she danced through the low gravity area in the Distortion World. It had been four years since her father had left her at the lake, for reasons still unknown to the legendaries.
This girl is quite a handful thought Giratina, although you could see a ghost of a smile on his face.
Harmony loved living with legendary pokémon. She had seen every one of them. From Mew to Arceus and everything in between, she loved them all.
She lives with them, on her secret island, most of the time. But occasionally, she goes to the Distortion World with Giratina, or swims across the ocean with Kyogre and several Manaphys, or travel across time with Celebi, and many other things with every legendary that exists.
She is already quite skilled for one so young. She had mastered the Azure flute a year before, to calm Arceus's lingering rage against humanity. She actually can use psychic attacks, but preferred not to fight with them, mainly because she didn't fight at all
Who would fight her though? She is only four.