The speedrunner z3r01337 found some interesting things with Seneca and Andarc's Cohort Attack--the damage formula seems to apply both their physical ATK and MAG stats, as increasing any of the stats leads to increased damage. It's very early in trying to figure out how the whole damage formula applies, but I suspect half the damage will come from the physical damage and the other half is magical... but how does the unite's own base damage come into play?
Also, perhaps this applies for all of the co-ops with a fighter and mage.
Cohort damage numbers: https://docs.google.com/spreadsheets/d/ ... edit#gid=0
Seneca + Andarc
Kyril + Corselia
Keneth + Katarina
Flare + Corselia
Coop + Andarc + Roget
Kika + Ornela + Jeane
Kyril + Seneca + Andarc
Millay + Rita + Corselia
And what about the Meow Attack with a support character, Noah...