My idea to hisui
when dialga ,palkia and,giratina agruging who have better ass giratine blast them both out of anger ,dialga see that and blast with time of roar which she dodge and the MC open the doorto stop the fight but got hit by dialga attack and that made he got sent back to sinnoh with no MASTER pokeball but he found a scientist who can help him ,he let the MC choose a starter but MC decline because he don't know how to fight pokemon ,the scientist see that just sighs and give him some pokeball , to help bre-tame the noble pokemon ,so the MC agree
Idk but does noble pokemon count but i said this because they gottq be extints so the MC know which help them