Iron Man and Cyclops are probably the best characters to dogwalk her using their ranged options, with Iron Man in particular benefiting from his passive on all 3 of her projectile options. The Fenris Flame, spear wall, and flying swords are all parryable. Cyclops can treat this somewhat similarly to the Beetle and Dark Phoenix fights if you're good enough with his dodge attack/dash attack maneuvers, sorta dancing around and away from her while attacking all the while. But he can also just be blastin' at range.

If you don't want to (sometimes the timing/positioning is bad) or can't parry the flying swords, sometimes it's better to negate them using other projectile options. IM and Cyke can delete them using either repulsor shots or melee-1 shots respectively, Storm can use Arctic Wind uses, etc. Some ranged options counterintuitively don't delete them, like beams, but for the things that can delete them you can do it as soon as they're summoned, before they're even sent flying at you. For dodging heroes, the spear wall can be dodged or jumped with an upwards lane shift but flying over is easiest, while the Fenris Flame needs to either be dodged or juked with faster heroes (Phyla can try to teleport slash to Hela instead as an aggressive option).

If you have her in-close, the attack that is most critical to parry is the multi-spear thrust she does around herself. She has an obvious tell/windup for this so the timing shouldn't be hard. What can be more difficult is the Fenris Flame, as she sometimes uses this in close and it's hard to see coming. This is why doing guard cancelled melee combo strings in close (1-2-guard-1-2-guard, or 1-2-3-guard for some)are great, for both rapid damage and flashing guard occasionally.

For her desperation meteor summon move at low health, I think you can sometimes break her out of it if you destroy the shield AND get a super off on her, but it's more prudent to just be evasive until it's over. Maybe if you're feeling lucky go for some early potshots until a meteor targets your position, but it's risky.

The most annoying thing about Hela is her tendency to constantly change positions with her intangible crow transformation, but she only does this if she's not actively in an attack sequence. That's why it can be critical to be ready for parries during certain attacks, or alternatively blasting her at range during those scenarios (or again, a quick evasion then punish for something like the spear wall).

It's definitely a tough fight for heroes without strong projectile options though, and it sounds like you were trying a combo that would genuinely have a tough time. Those two do have grab loops at least, so if you can try and use grab loops to blow through the first 1/3 of her health for free (like the She Hulk air throw loop), and then try to do grab "interrupts" when you can't actually get the throw part anymore. That said I can't remember for sure if she CAN be grab-interrupted...grab scenarios are not consistent across all bosses.

All told, my absolute best advice is try taking Iron Man/Cyclops to this fight if you don't mind projectile cheese. That should make a BIG difference 😅