There's already a bunch of mechanics ingame to answer that demand.
Catgirl can be trained and befriended, leveling her up in the process and making her weakness less of a problem for her.
The labyrinth has an option to sync enemies' levels to yours, making the weaker ones of the early game a challenge once more. Kinda. After all they will only have thei usual abilities while you'll have a plethora of skills to deal with them.
I assume that the twins will be added (or are already added) to it at some point. Demanding special beefed up versions of certain fights is not unsual for this game btu not everybody can get this treatment, there's not enough time in the day.