My idea for the opening in full.
Arrive in Hiun city, get off the boat, and be stood on the port, be welcomed to Hiun City and the Isshu region. Have a little explore, some parts of the city might be closed off for some reason/people in the way etc. Meet Proffesor Tree and help her with something, (maybe pat her on the back to cure her sea sickness as a reference to kanto games, lol, you get the idea, a very small task, not a challenge at all) then the professor will be all like "I see you don't have any Pokemon, come to my lab in Somewhere town to get one."
She disappears, and you have to go and find that bridge, over the bridge and into that small little starter town looking village find the lab and get the starter. Then she'd be all like, "want to know why I was in Hiun I just got back from the Kanto region to pick something up from my friend Proffesor Oak, its an all new pokemon encyclopedia" hands over Pokedex, "we were wondering if you could fill it up with all the Pokemon in Isshu" And off on your journey you go.
Arrive in Hiun city, get off the boat, and be stood on the port, be welcomed to Hiun City and the Isshu region. Have a little explore, some parts of the city might be closed off for some reason/people in the way etc. Meet Proffesor Tree and help her with something, (maybe pat her on the back to cure her sea sickness as a reference to kanto games, lol, you get the idea, a very small task, not a challenge at all) then the professor will be all like "I see you don't have any Pokemon, come to my lab in Somewhere town to get one."
She disappears, and you have to go and find that bridge, over the bridge and into that small little starter town looking village find the lab and get the starter. Then she'd be all like, "want to know why I was in Hiun I just got back from the Kanto region to pick something up from my friend Proffesor Oak, its an all new pokemon encyclopedia" hands over Pokedex, "we were wondering if you could fill it up with all the Pokemon in Isshu" And off on your journey you go.