I suppose giving
Balancer a proper rating would be good.
As first evidence, they can control magic in a fashion too complex for humans to handle.
A few more interesting points are raised during a Ping-Pong match between them and the christian god. See the bolded parts for the most interesting bits:
In summary:
Even during the Earth Age, about a thousand years ago, Balancer already had processing power superior to the human brain.
Doing the physical calculations for ping-pong in real-time is easy for them even when restricted to a fraction of their full processing power.
Balancer created the gods by extracting them from the concept laws, which demonstrates conceptual technology (although it's impossible to say how much of that already existed - in principle Balancer itself is the culmination of humanity's technology)
Can calculate out other people's thoughts with a high certainty, but not perfectly due to true free will. Ultimately, they instead simply calculate out countermeasures to all possible and impossible options, as that's easier than determining thoughts.
Considers Shogi (japanese chess) an easy game which can be thought through (i.e. solved) quickly.
In addition to that, they have the awareness to handle the data of knowing everything that is going on in the Japan-sized pocket dimension, down to every last breath.
Also has a database with information, as one would expect from an AI.
And, given that he made a convincingly real pocket dimension version of 1990 Japan, that Database should have a wide raneg of information.
I think overall that's just enough to be considered an extraordinary genius by human standards.