When I first saw Limitless Stamina and Unshakable I thought these cards could help Hulk be a little less awful, but unfortunately, they boosted other 14+HP heroes, while leaving Hulk pretty dreadful.
I have to state the obvious: Hulk just has too many drawbacks. And that is baffling, considering that, apparently, he was designed as a "fun" and straightforward character for kids to play. Scenarios get more difficult, other heroes get buffed here and there, but Hulk remains a frustrating puzzle with basically no right answer that doesn't rely on luck of the draw.
The only hope I could potentially see for the Green Giant would be introduction of permanent cards that are played for free from your deck at the start of the game and having one designed specifically with Hulk in mind.
My proposal would be simple: "Gamma champion" - [Permanent. You may include this card in your deck only if your hero identity has a "Gamma" trait. +1 hand size. When in hero form, all your hero cards cost one less.] This may seem like an incredibly overpowered card and it is, but considering that the only two heroes in the game (at the moment and probably for a good while) with "Gamma" trait are consistently considered to be among the weakest, I think only such a radical step would help these characters in a significant way. And even then, it would bring them merely closer to the average overall, nowhere near close the likes of Doctor Strange or Captain Marvel. An alternative to cost reduction would be either built in Plan B effect, increased ATK stat or piercing for basic attacks, but I'm pretty sure these options, while more balanced, wouldn't be enough to make Hulk relevant.