Normal Grade: In terms of strength, they are usually C-Rank or below. He doesn't have any of it.
Elite Grade: Elite Grade shadows are the most common shadows in the Shadow Monarch's army and are about as strong as B-Rank Hunters.
Veteran Grade: Below A+ Rank Hunters
Knight Grade: Knight Grade Shadows are about as strong as A-Rank Hunters. Shadows of this grade or higher are also able to be named.
Veteran Knight Grade: A little higher than A+ weaker than S- - -.
Elite Knight Grade: Elite Knight Grade Shadows can be as strong as weaker S-Ranks like Baek Yoonho .
Veteran Elite Knight Grade: Just a little bit weaker than the SS-Rank hunters.
CommanderNV/GeneralWB Grade: General Grade Shadows are incredibly powerful, with some even strong enough to easily overpower S-Ranks as strong as Goto Ryuji. Or nearly touching boundaries SSS
Grand CommanderNV/GeneralWB Grade: Grand
General Grade Shadows are incredibly powerful, with some even strong enough to easily overpower S-Ranks as strong as Thomas. Or going beyond SSS++
MarshalNV/CommanderWB Grade: Marshal Grade is the highest grade that a shadow can evolve to. As a result, shadows with this grade are some of the strongest just a little blow that EX Rank.
Grand Marshal Grade: Grand-Marshal Grade is the highest grade that touches the walls of L grade. Able to destroy multiple planets.
Great Grand Marshal Grade: Strong enough to destroy solar systems. X-Rankers.
Z-rankers now words don't hold meaning as they are strong enough to nearly destroy galaxies and shake the universe.
Transcend- Multi Universal level going beyond a level that is hard to define.
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More will come if fanfiction continues