I have mained her since the launch. I will willingly debate why each MU is so.
SG vs ____
Aquaman: 5-5
Atrocitus: 5-5, but hard. Supergirl has a slight advantage
Bane: 6-4
Batman: 4-6
Black Adam: 5-5
Black Canary: 5-5
Black Manta: 6-4
Blue Beetle: 7-3
Brainiac: 5-5
Captain Cold: 6-4
Catwoman...