So, the unit ranking for max 6star units is up in the Playbook.
The criteria i used in this first version for scaling:
STATS (only base stats without passives or equip)
HP
E: 3299 or low HP
D: 3300 - 3499
C: 3500 - 3699
B: 3700 - 3799
A: 3800 - 3999
S: 4000 - 4199
SS: 4200 and up
MP
D: 210 or low MP
C: 211 - 219
B: 220 - 229
A: 230 - 249
S: 250 - 259
SS: 260 and up MP
ATK
D: 139 or low ATK
C: 140 - 149
B: 150 - 159
A: 160 - 169
S: 170 - 179
SS: 180 and so ATK
DEF
D: 129 or low DEF
C: 139 - 130
B: 140 - 149
A: 150 - 159
S: 160- 169
SS: 170 and more DEF
MAG
D: 139 or low MAG
C: 140 - 149
B: 150 - 159
A: 160 - 169
S: 170 - 179
SS: 180 and more MAG
SPR
D: 139 or low SPR
C: 140 - 149
B: 150 - 159
A: 160 - 169
S: 170 - 179
SS: 180 and more SPR
DAMAGE SKILLS
Damage skills is a total arbitrary ranking, but it can be standarized after asking the following questions:
1.- Total % (after DEF/SPR reduction) of most powerfull skill
2.- Number of alternative damaging skills the unit has
3.- The unit has only neutral skills? or only elemental skills? or both? (Yes to third alternative is more score than yes to first and second)
SUPPORT SKILLS
Support skills is a total arbitrary ranking, but it can be standarized after asking the following questions:
1.- The unit can heal? If answer is YES, what is the quality of the healing? (cura lvl? curaja lvl?, ST cure? AoE cure?, can it be dualcasted?)
2.- The unit can revive? If answer is YES, what is the quality of revive? (raise? reraise? ST raise? AoE raise? can it be dualcasted or dualcast the revive and a healing skill?)
3.- The unit can tank? If answer is yes, what is the success of tanking skills?
4.- The unit can clear ailments? How he/she clear ailments? (ST, AoE, All ailments in a single skill, only some ailments. Only to party members? Or enemies too?)
5.- Does it have unique suport skills? (Bartz Sacrifice for example)
BUFF SKILLS
SS: +45% or more to all status
S: +40% to all status
A: Embolden, deep blue, or similar
B: Cheer, Focus or similar
C: Any buff lower to B,A,S,SS
D: Zero buff skills
DEBUFF SKILLS
SS: Can debuff Stats, inflict ailments and elemental resistance
S: Full break or 50% or more debuff to 3 or 2 stats or elemental resistance
A: 40% debuff to a stat or elemental resistance and inflict ailments
B: Can inflict ailments but no debuff to stat or elemental resistance
C: any debuff skill lower than B,A,S,SS
D: Zero debuff skills
LIMIT BREAK
The usefulness of the LB is arbitraty, but if the skill is good AND has fast lb charge, is S or SS ranking. If the LB is good but unit doesnt have fast lb charge (innate or via skills) the LB max ranking is A.
Is a LB is good or awesome but takes more than the standard 16 LB crystals to charge and doesnt have fast lb charge, the max ranking is B (see noctis LB ranking)
This is the first version i it needs to be polished more, but i expect your thoughs.