Played an aquaman in tournament the other day, its definitely an un-winnable match up. First off, aquamans normals can keep us out, his range is a bit better, meaning we can only go for a b1 since it has the longest range, which is an easy duck block, and has no follow up pressure - unless i know they try to counter poke then i will go for Flying Bat (can be risky but it sure beats ALOT of counter poke attempts with its 6f start up.) but i do this against anyone. All that does it stop them from counter poking, still neutral.
Second - when we do actually manage to get him in the vortex, he will simply trait and he is out of it. Batgirl without vortex is crap, she has very little damage (unless in the corner) and she doesnt have any block strings to carry on pressure.
This match up...you need someone else to fight him because batgirl wont cut it.
Aparantly it's not unwinnable, although I've yet to win against any decent aquaman. It's definitely her worst match up though. Go for the b3 from bola instead of vortex cause he'll trait out of it. Or grab him instead. Once trait is out pressure.
Always go for damage, not vortex. 1 hit launchers beat trait. That means the following combos;
b2u3, ji2, f23~df2 (MB), 212~db2u (42%)
b12, f23~df2 (MB), 212, db2u (38%)
b2u3, b2u3, ji2, f212~db2u (36%) meterless
b12, b2u3, d2~bf1, dash, b3, ji2, 212~db2u (31%) meterless
d2~bf1, dash, b3, ji3, 212~db2u (24%) 1 hit launcher meterless
df2 (MB), f212~db2u (28%) 1 hit launcher
f3, ji2, f212~db2u (31%) 1 hit launcher
f3, f23, f23, f23~db2u (43%) 1 hit launcher meterless corner (although you'll prolly MB the f3)
df2 (MB), f23, f23, f23~db2u (47%) 1 hit launcher corner
f3, f23, f23, f23~df2 (MB), f23~db2u (52%) 1 hit launcher corner
When he does scoop, dash up and df2 to punish; MB for a combo. Same with trident rush, duck the last hit and punish.
If the aquaman traits too early (ie when they're in the bola) dash forward and wait for them to break out, the continue the vortex with either starter.
But in all seriousness, I just use a secondary. I'm trialing WoWo and Frost because for babs, the aqua MU is (IMO) a 7-3 at best (although I keep hearing it's a 6-4 lol).