Thoth not released to PS yet, and Camazotz is not played enough for me to get an accurate reading of him in arena.
This is all based on my opinion and is free for interpretation.
SS Either Focus these two or die.
S+ Super Potent can swing fight
S Potential to swing fight in certain circumstances
S- Very strong may swing fight from time to time
A+ Great depending on team composition
A Can be viable in arena but are not the best
A-,B,C Too easily focused and killed to be viable in arena