Every unit in FFTBG has a zodiac, based directly off of astrology. These signs determine the compatibility between units, which affects hit percentages and damage or healing.

If a unit has good compatibility with another unit they will do 25% more damage to them. Good compatibility is based on the trine aspect in astrology.

If a unit has bad compatibility with another unit they will do 25% less damage to them. Bad compatibility is based on the square aspect in astrology.

Best and worst compatibilities are based on the opposition aspect in astrology, but come with an addition clause, dependent on gender.

• If the unit is the same gender as another unit, they are the worst compatibility, and do 50% less damage.
• If the unit is the opposite gender as another unit, they are the best compatibility, and do 50% more damage.

For example, a Red Panther with the sign of Taurus would have the worst compatibility with a Floating Eye with a sign of Scorpio and the best compatibility with a Summoner with the sign of Scorpio.