Zi Fighter

Zi Fighters are a class of Zoid Pilot from the Zoids: Fuzors anime.

Overview

A Zi Fighter is a registered Zoid pilot with permission to equip their Zoid with weapons for use in sports combat. Civilians are restricted to using only unarmed Zoids.

It would seem the license requires proper testing to acquire, and in Blue City can be suspended/revoked by the authorities (aka the Peacekeeping Bureau).

ZAC 2230, on the Eastern Continent, in Blue City

This is a peaceful age where Zoids aren't used as weapons, but for transportation, public works, and keeping the peace. Only certain people are given permission to equip unrestricted armaments on Zoids: Zi Fighters. These are Zoid pilots possessing the qualifications to participate in Zoid Battles—grappling tournaments using Zoids. Winners are awarded large sums of prize money and honor. Zi Fighters know a strong power arises from making Zoids unite together (aka "Unison"), and search for powerful Zoids that can combine...

(Rough translation of the "Fuzors Story" fluff seen on the model kits released during this era)