High Spec grants Nezu, who was formerly a regular animal, an intelligence surpassing that of normal humans. Through this Quirk, Nezu became capable of thinking, speaking and acting like a person.
Due to his high intelligence, Nezu is capable of formulating incredibly intricate battle strategies; allowing him, from a single vantage point, to destroy an entire industrial zone along a designated path from just one well-placed construction ball smash. This same intellect also grants him great leadership skills, which are acknowledged by the fact that he is the principal of U.A. High, a top hero school.
Perhaps because of his acquired intelligence, it is also possible for Nezu to hold grudges and other negative feelings that are exclusive to the human species, which might interfere in his thought processes.