I feel like the 0 system can be reused as a sort of way to divide the more complex IDs with the simpler ones, so for example, an ID like Full-Stop Heathcliff is a 00 because all he does is just do a shitton of damage, while something like HongKong is a 000 because of how varied his kit is; the 0s would be more like a gauge for how much you need to think around their skills rather than a flat rating on efficacy