Not sure it requires a entire game of focus, but it would be fun to stockpile enemy abilities and select which ones you want to use almost like the KH2 enemy reaction commands, only using them without the enemy triggering it. Maybe that's just the FFV fan in me begging for Blue Mage/Mime style powers to be playable.I had an idea/vision of a game around Xion copying powers from other people that is just gold gameplay for me to ignore that justifying a game with her playable all the time.
They could go all the -Mario Odyssey- and find a fun way to make her copy some enemie's powers for attacking, magicking, and spelling! I don't even love her outside of Days, but can you even imagine ???