So I kinda based this idea off DnD and Pokemon.
So basically you have HP (Health Points) and PP (Power Points, or how much stamina you have) that's a pretty obvious thing to have in battle though. Each character (except kits) have a certain amount of move slots. Apprentices will have 2 move slots, Warriors will have 4 and Leaders have 5. You start out with a basic move set but using CC you can upgrade moves or change them, so an apprentice will start with two basic moves like "Scratch" and "Kick" but depending on their PP when they choose to upgrade they get better moves that deal more HP damage. Maybe you can add two items to the shop "Randomise Scroll" randomises one of your moves or you can have a straight up list of moves, each costing a certain amount of CC.
Maybe at the start of the battle everyone rolls a dice, maybe using a dice roll website, they have to screenshot as proof and use imgur or some other image hosting website. The lower number is the last person to move. Maybe also roll a dice for accuracy hits too, like DnD a D20. 20 being a critical hit, 1 being a miss. This would also allow for certain moves like "Dodge" to be implemented, dodge could be a move where if your opponent hits 10 or lower you dodge their move. If needed I could probably come up with a TON of moves, already got my mind racing now lmao. The only real problem with a dice system online is you're never sure if someone could be lying, you have to take their word for it and not only that online dice aren't truly random.
But yes, there are my ideas, sorry for the rant, rant over.