>>51821570the gap between volkner and cynthia in dp is 17 levels, which is more than any other gen. they even realised how stupidly unbalanced this was and lowered cynthia's levels in platinum, even after raising volkner 1 level.
by the time you get to cynthia in dp, you'd likely be around the early-mid 50s. that's where the challenge in pokemon comes from; being underlevelled compared to the enemies.
your gif shows that you clearly grinded an unreasonable amount to match cynthia's levels thus mitigating any challenge that comes with the fight.