To be honest I think resetting to 0 or blacklisting is not enough of a deterrent for cheaters.
I'm taking an example from another game I played a long time: Maplestory
maplestory used to be strict on cheaters, you get caught you get permanently banned.
After a while they let up on cheaters, making the ban shorter and shorter.
The only result it got (instead of bringing people back to maple) it made the cheating community expand tenfold.
Cheaters only listen to one thing: the threat of losing everything they cheated for.
I guess you should make a rule:anyone suspected in cheating will have his/her battle point reduce to one every match so that they will be annoyed and they will stopped cheating. In that case, cheaters will be reduced and soon will stopped cheating. Even if they K.O. their enemy or level-up their cards, they will always get one battle point.. That's just my opinion. I hope its helpful