Well, if Harry Potter were to fight the Hulk in fanfiction, Harry would likely be at a disadvantage initially. The Hulk's brute strength is on a whole different level. But Harry is smart and resourceful. He might use his invisibility cloak to get close and then hit the Hulk with a powerful blasting curse. The Hulk, though, would probably just get angrier and more powerful. It would be a really interesting battle to read about, with magic vs raw physical power.
In this kind of fanfiction, Harry could potentially use the Hulk's strength to fight Voldemort in a very different way. He might be able to smash through dark magic barriers with ease, and his rage - like the Hulk's - could be a new source of power against the Death Eaters.
If Harry Potter fights Imhotep in fanfiction, Harry would likely start with his go - to spells. He might try a Stunning Spell or a Shield Charm. Imhotep, on the other hand, would probably use his powers of necromancy. Harry would be at a disadvantage in terms of not being used to dealing with an enemy who can raise the dead. However, Harry has the advantage of speed and agility in combat, which he has learned from his years at Hogwarts. So it would be a very interesting fight to read about.
If we consider Harry Potter fighting Thanos in fanfiction, it's a clash of two very different universes. Harry has his wand and his knowledge of spells. He could try to transfigure Thanos into something harmless, but Thanos' willpower might resist such magic. The Time - Turner could also be a factor if Harry could use it to his advantage, perhaps going back in time to prevent Thanos from getting the Infinity Stones. But Thanos' brute force and his army could pose a great threat to Harry. It would be a battle that would depend on Harry's quick thinking and ability to adapt his magic to this new and powerful enemy.
In this fanfiction, Harry might use his magical skills like the Patronus charm to fend off the dragon. Maybe he'd also rely on his broomstick flying skills to dodge the dragon's attacks.
In a fanfiction scenario where Harry Potter fights the Night King, it could be a very interesting battle. Harry has his magic skills like the Patronus charm which could potentially be used against the Night King's army of the dead. However, the Night King is extremely powerful and has the ability to raise the dead. Harry would need to find a way to counter this, perhaps by using powerful offensive spells like the Killing Curse. But he would also have to be careful not to get overwhelmed by the sheer number of the Night King's forces.
Harry would probably start by trying to understand Thanos' powers. He might use his invisibility cloak to get closer and assess the situation. Then he'd likely use some of his most powerful spells like Avada Kedavra, but it might not be as effective against Thanos as it is against normal foes.
A 'Harry Potter is the Hulk fanfiction' could be a very interesting take on both universes. Imagine Harry being in Hogwarts but having the Hulk's abilities. He might accidentally break things around the castle when he gets angry. His professors would be puzzled on how to handle this new situation. And in battles, he could be a one - man army. He could jump great distances like the Hulk and at the same time use his Patronus charm. It would be a story full of unexpected twists and turns as he tries to balance his two very different identities and powers.
In a fanfiction where Harry Potter fights Sauron, Harry would be at a disadvantage in terms of raw power. Sauron is an ancient and extremely powerful being. However, Harry has his courage and quick thinking. He could use his ability to solve mysteries and puzzles. He might figure out a way to destroy the One Ring, which would be a huge blow to Sauron. But it wouldn't be easy as Sauron would be constantly trying to stop him.
Well, in such a fanfiction, Harry might use his magic skills like the Patronus charm to fend off the Volturi's attacks. Maybe he could also team up with his Hogwarts friends to create a powerful defense against the Volturi's mind - control powers.
It would probably be really wild. Maybe Harry Potter gets cursed and turns into the Hulk - like creature in the wizarding world. He could use his new - found strength to fight off dark wizards in a very different way than with his usual magic.