>>56628793https://tcrf.net/Development:Pok%C3%A9mon_Diamond_and_Pearl/DocumentsThere's several versions of the myth, and several versions of the giant. They all use the same Japanese word, kyojin, that can translate to giant or titan. To sum the different ones up
>Reek, a primordial giant who gets dismembered by two gods, one human and one pokemon, in order to create the world and various gods>several giants that are born from arceus' egg fragments that attack him, and are defeated and used to create dialga and palkia. there's another version where it seems there's only one giant, and that giant is also used to create the lake and weather trio>a giant created by arceus to destroy walls and expand the universe. it turns on arceus and wants to destroy everything, and arceus can't defeat it. arceus has dialga and palkia with a human that defeat the giant. the giant's corpse becomes mt. coronet>a black giant created by arceus as dialga and palkia's brother. his purpose is to shatter the egg of life that contains all humans and pokemon. he starts killing them, and dialga and palkia create the lake trio to help a human slay him. mourning their brother, they share their souls with him, and his body becomes the world and his soul becomes the weather trioAs you can see, a couple versions make the giant sound like Giratina, and a couple versions more like the Regis. Note that there is a footnote that explicitly says the giants aren't pokemon. But who knows, that might have been changed too, none of this was set in stone