I'd say she's stronger. I have nothing to base this on except for the fact that BD/SP is coming out in a few months but since it is, I can easily see her being Leon's equal in a 6-on-6 match. In a 1-on-1 Dynamax/Gigantamax battle, I think Leon would definitely win, though in a closer match than one would expect. In a 6-on-6 battle without Dynamax/Gigantamax, I see Cynthia pulling out the win with difficulty. In a 6-on-6 with Dynamax/Gigantamax battle, I see it ending in a tie. That way, neither Cynthia nor Leon looks bad. BD/SP is represented well via its Champion and Leon is not shoved aside for the newest series of games. In addition, such a scenario allows Leon to still be Ash's ultimate goal for Journeys while allowing Cynthia, or a potential future Champion from either Gen 9, a past Generatiion (like Steven or a potential appearance by Leaf representing Kanto (please let this happen)), or both, to be the ones to show that while Ash has come a very long way, there's always a stronger trainer out there if he does want to become the strongest (which is not yet a stated prerequisite for becoming a Pokémon Master).this is a situation where i would need to see them fight to get a clear indicator of where she stands.
if the anime was that comparable to the games, pokemon wouldn't be dodging moves. since that's not a thing outside of using moves like Double Team
If anyone has seen SM and saw what that attack was capable of doing, then it's not exactly hard to register that it could override Electivire's Motor Drive all things considered.