HG does have tools for Supes air zoning and repetitive f2,3 breath. She can down 1 i between w/o having to time it and be at plus 16. That being said Supes can bait the d1 and whiff punish with, of course, f2.
B/C HG flies so slow and can't hit you with down Mace Throw from full screen. You can use DJT like patience and just spam FULL SCREEN projectiles faster than she can and beat her in meter building. This will force her to come to you. If you jump over 1 down Mace throw as she is approaching she is in trouble due to her recovery. Like Art said, she has problems with midscreen damage so if you get 1 combo off and do this with clock management... it's a relatively easy win.
I co-main HG and only beat good people who are unfamiliar with the match up. She's not that good, but I refuse to drop her. Almost everyone can interrupt her WE after a block strings as well. I've taught some people how to deal with the match-up and they bodied her at EVO. She's an odd character so I recommend you find a HG player to explain the match up to you and get experience (like Bob in Tekken, but she's not top tier). You'll, see flight is just a gimmick. Also certain characters can feel like an 8-2 or 7-3 against her b/c the completely negate flight like WW, BA, SIN, GL, BG, Bats, DS, LL, Cyborg etc. Still props to Husky Brown for putting down the EVO champ once.
good showing !!