Super Alloy Z (Almost unbreakable hull)
Photonic Energy Reactor (Almost Infinite Power Source)
A wide variety of weapons that are proven to destroy other robots as fast as Yamcha dies against a Saibaman.
Is a pick your poison situation, get frozen, cut, melted, rusted, exploded or just rammed through. The Kaiser Blades are made of the same nigh-invulnerable alloy as Mazinkaiser itself, only that sharpened.
The Photonic Reactor allows attacks of incredible power. Not to mention the most iconic and intelligent of the Mazin series robots weapon. The Rocket Punch, in this case with a drill and can be controlled by Koji (pretty adept on it) from afar to home into the opponent. Juzo Kabuto is an unknown genius, he thought "Why punch a foe close combat if you can punch the fuck out of him from 3 blocks away"
We shouldnt forget that Mazinkaiser can also fly, and use his scrander as a weapon.
Not to mention Koji haves at least 3 years of experience piloting mechas and is known to be an all-around good pilot.
Basically Kamina is screwed as Gurren lacks ranged attacks except for improvised ones and isnt even as durable as the basic Mazinger Z. With the advantage over terrain thanks to his flight capabilities, durability, weapon variety and piloting skills Koji and Mazinkaiser will destroy Kamina.....
One Fire Blaster, Turbo Smasher Punch or Photonic Beam that connects and Kamina is dead. If Kamina miraculous manages to take the fight into close combat the assortment of Kaiser Blades and the Kaiser Knuckle are more than enough to turn Gurren into a pile of scrap not even worthy of being used as scrap parts for Boss Borot. And the Kaiser will do this while tanking Gurren attacks thanks to the insane durability of the Chokogin Z