I think Ash should get at least 2 starters in Isshu. Besides, Ash got all theee starters in Kanto and Johto. I hope he gets the grass and water types, but he will probably get the water and fire starters. I agree that it looks like Pokabu is in a gym battle when it was shown.
At first I thought that this "legendary" was going the be the Isshu rat pokemon evolution. I don't think it will be very strong or useful. Maybe it will be the first evolving legendary?