Even if this female character has the other form of Urshifu it does not mean that Ash can’t get one latter in a future episode since Kubfu has not appeared. Also just because a pokemon has appeared in a episode does not mean that a different one can not get captured in a future episode as we have seen this with Goh’s captures multiple times now like Mankey for instance. My theory is these characters are only here for a project Mew arc. I still expect a future IOA arc and CT in a future episode that focuses more of those areas. Since Leon is a main focus of Ash in this series then I expect Mustard to show up eventually since he is Leon’s mentor.Honesty I wouldn’t be that surprised if the Rapid Strike Style goes to that new female character who has the color blue on her clothing. Heck they could even have her kill two birds with one stone by having her have a Kubfu that winds up evolving into Urshifu Rapid Strike Style.