Gen 9 had some amazing original mons. My favorites being Arboliva, Garganacl, Tinkaton, and Skeledirge for example. However I’d say mon wise the biggest miss was their generational bird and pseudo legendary. Kilowattrel barely counts as the gen bird, and despite being excited for Baxcaliburs design, he just doesn’t give as cool of vibe in battle as most of the other pseudos.
Plus the treasures of ruins feel incomplete. They have a cool concept where they’re just straight up cursed spirits, but the designs feel like they have no aura and their story feels like it should’ve been expanded upon in the dlc rather than the (even worse) loyal three.