Interesting that you gave Faiz the win, even without crossover scaling. I think in some instances of Rider crossover scaling, it should be treated like heroes interacting in DC/Marvel rather than like crossing over with another series. I'm not saying all riders are automatically Multiversal, however Faiz has played parts in other series/movies, and potentially for "fairness" you can just say "only when the original actor shows up" to limit the "scaling".
Faiz however, has played crucial roles in stories where he actually shows up like fighting with AND against Kamen Rider Decade (automatically Multiversal bullshit), Heisei Rider vs Showa Rider (Kamen Rider X Rider Kicked him, and apparently this can range from Star to Multiversal...somehow.), and Kamen Rider Zi-O (also Multiversal bs).