Having played through both Normal and Intense mode, i'd say everybody was just right, except Crawli, Narcissa, Venam, and Valarie obv. Crawli is a pretty easy gym leader, if you have the right mons. Intense Crawli could be a bit more challenging like his freakin gym puzzle lol. He really doesnt have any huge threats aside from maybe volcarona and yanmega, but even then if you have rocks then those threats are gone.
Venam is the first gym so I understand that you cant make her super hard OP, but Intense Venam was a pushover, im sure the AI system had played a small part in that battle as well iirc, like wasting potions and making unnecessary switches.
Intense Narcissa was also pretty medium. Tbh I think Pre-nerf Narcissa from V4 should come back for Intense mode, as much hell as she was lol, it was definitely challenging, and Jan has put in a lot of new pokemon, so maybe it won't be near impossible to win now.
As for Valarie(intense and normal), Im sure she's already gonna catch the nerf gun real fast, battle was fun, but very difficult.