Right so disclaimer: I am not a tournament player, while I would love to go to locals and be a part of the scene, college and lack of knowledge of local areas prevent me from doing so. So therefore most of my experience comes from online and while Injustice online is serviceable (at times) it does not hold a candle to the game that Injustice is offline. So do take what I say with a grain of salt as I may not be playing/facing the styles offline players will encounter. That said I love Captain Marvel and want to add what I can to the forums...
Further disclaimer: The Hawkgirl matchup is bullshit, I'm talking cartoon Texas, wild untamed west frontier bullshit. Explore counterpicks or your secondaries. Hell, pick instawin Supes to save yourself the frustration. As for me, I'm an idiot with a blind love for Captain Marvel. So if by chance you do pick Shazam...
Pick a favorable stage. My best result was with Ferris Hanger, don't give two shits what people say. Interactables are in the game so use them. For Hawkgirl aim for one with plenty of stuff to throw to blow up her generic approaches (because as decent as they are, they are simple and as one track as a slot car) preferrable one in the corner and respawns for your use.
EX: After a combo ending with MB Torpedo I ended up in the corner in the Batcave and Ferris aircraft. Both Batcar missiles and aircraft missile dealt that extra damage that seemed to blow up her wakeup. Turbine was especially fun to use at times as well. Time them to catch her out of the invincibility of her wakeup moves.
After playing a Hawkgirl online for practically 20 matches or so, I almost threw in the towel. Haha her mace charge is so annoying. But from what I can tell...
Mace Charge: Watch the range she does it at, Far range B2,1 is a weird punish. By this I mean it sometimes catches people for the first few times... but that's if they are being reckless and don't expect the punish. If for whatever reason Hawk does it up front, reversal HM. Not sure on MB Charge but it's what worked for me. A wakeup mace charge is trickier. Sometimes you can jump over and a j2 will hit her out of it, but mostly you'll just get hit. I found that a properly timed Torpedo caught her in the startup. IDK for sure what it was but hey it worked so I'm not complaining. The real easy way out I feel is a meter burned b3. However keep in mind that MB Mace Charge blows that up so watch her meter bar as well as yours. What I also found is that his weird Teleport property works here as well. So if you can time it, teleport through it. Don't know about punishment yet... working on that.
Flight: Watch what the Hawk does in flight. The few that I've fought that used her above average, used her divekick a lot. While it may seem hard to reach her. J1 worked wonders for me. Just be patient and watch what she does. If she doesn't have meter or does not use her Mace throw MB, meter burn B3 to catch the Dive. If you can position the 3 part of B23 seems to catch her a lot. But B23 is a bad habit to get into so I digress.
j D2: Fuck this moves chip and advantage seriously. Meter burn B3. If you can properly use it, time Shazam's D2 to hit her as I caught her a few times. Try backdashing if you can to make her whiff and then punish her for it. Not sure on whiff recovery for the move, but on block the Hawk's I've fought Mace Charged right after so be wary of that.
Mace Throw: Seriously the one I fought rarely used this outside of MB. However whiff punish it hard. It's high so you can duck the ground one, so duck then Torpedo provided Hawk does not have meter. If the Hawk is in the air just dash it, it's pathetically slow. Just keep in mind, Hawk's position for the punish after you avoid that laughable mace projectile.
Notes: Hawk's super is overhead, not a throw and/or regular hit. It's half decent unlike the garbage that is Shazam's. I believe it also leaves her airborne so think Superman but overhead I guess.
Strings: I rarely see these used but if they even start a string for some reason at a distance, torpedo them. MB if you can to put you near a throwable interactable. I can't say much as I don't have much experience with them. I want to think they are backdashable but I don't know for sure. Block high for the most part, her lows chain are telegraphed and most of her strings generally start or the 2nd hit will be Overhead save for one 2nd hit which is the low chain. Punish gaps if you can with HM or just sweep her.
