I would like the enemy cards to return, because I feel that being able to have enemies aid you in battle is one of the best things in Colour Splash, even though its limitations prevent it from being utilised well (namely: one battle use and auto-runs from bosses). Perhaps they could provide a capture system (maybe with a new camera item?) that allows Mario to snap enemies and add them to his roster, similar to Pokemon.
On a side note, it's cool how most of Paper Mario's enemies are redesigned to look more like the original counterparts (see Pokeys, Spinys and Buzzy Beetles for examples). I hope they add more of the Super Mario enemies (and one or two Yoshi's Island ones) because we have a breadth of them to pick.
Thank you for reading.