Thinkin about aragoto as a (ceremonial?) Dragon Clan tradition, with kumadori as a generally less formal (maybe for celebrations/festivals) but still culturally significant custom....
And then also Clair incorporating it into her gym leader uniform?
Lance would probably also have some, but significantly less dramatic just because of personal preference. Like maybe just some eyeliner, something a little more obscure.
I think the ipponguma would also be a better fit personality-wise, but realistically he'd probably reference the nihonguma style just as part of the more "respectable" image he has to portray as champion.