My friend and I have been playing through the game and while we love the story and charming writing many of the battles on hard mode seem to be wildly imbalanced when comparing the pokemon offered and available at certain points to what you're expected to fight, I'd recommend taking a look at a few of the early game fights to rework the scaling as much of the difficulty of hard mode is less about the actual team comp the other trainer has and moreso them just having objectively stronger pokemon, its unfortunate as currently the hard mode difficulty feels the way it does less from strategic team setups and moreso frustrating differences in pokemon.
Though for context my friend and I have not been utilizing the starters on our run and this review is currently being written at the end of Case 4