I think Harry would also clone Dumbledore. Dumbledore was one of the most powerful wizards. His wisdom and ability to see the bigger picture would be invaluable in the clone army. The clones could guide others and make important decisions, just like the real Dumbledore did.
Another likely candidate could be Sirius Black. He was a brave and loyal friend to Harry. His skills in combat and his ability to think on his feet would make the clones of him great fighters. Also, his loyalty would ensure that the clones would be dedicated to the cause Harry is fighting for in the fanfiction.
Definitely Hermione. Her intelligence and vast knowledge of magic would be a great asset if cloned. She could help solve complex magical problems and come up with strategies in battles.
He could have found a magical artifact. There are many artifacts in the Harry Potter world that have strange and powerful abilities. It could be that this artifact has the power to create clones. He figures out how to use it, perhaps with the help of Hermione who is good at researching such things. And then he starts creating his clone army.
In the 'Harry Potter makes a clone army fanfiction', perhaps Harry creates the clone army to protect Hogwarts. He might use some ancient magic spells he discovers in the library. These clones could be modeled after the greatest wizards in history, like Merlin. They would bring a whole new level of defense to the school against the dark forces.
It could also change his relationships. His friends might be worried about this new and rather extreme power he has. They might question his motives and whether this is the right way to deal with the problems in the wizarding world. On the other hand, his enemies would definitely be more cautious around him.
I think Dumbledore might be a candidate in the fanfiction. He's the most powerful wizard of his time and could offer Harry deep insights into magic, history, and the fight against the dark side. Also, Luna Lovegood could be a tutor in her own strange but brilliant way. She has an unconventional view of magic that might open new perspectives for Harry. Then there's Sirius Black. He could teach Harry about the wizarding world outside of Hogwarts and some spells and tricks he learned during his time as a fugitive.
Hermione Granger might also be a key character. She could be involved in researching the theory behind the shadow clones and helping Harry control or improve this new form of magic.
The originality of the story. Harry Potter has a unique plot that follows Harry's growth and his battle against Voldemort. This is not a recycled or cloned idea.
A half - blood character could be the main character. They have a connection to both the magical world of Harry Potter and, through some strange family heritage, to the Clone Trooper world. This character could be on a quest to find a way to merge the two worlds' strengths, believing that the combination of magic and Clone Trooper technology could bring peace to both universes. They would face opposition from those who fear change and from dark forces in both worlds.
Another possibility is Winky. She is also a house - elf. Winky was a bit of a tragic character in the original books. In the fanfiction, if Harry were to summon a servant, her meek and somewhat lost nature might make for an interesting addition to Harry's side, and she could be summoned to help Harry with various tasks.
Voldemort would still be a very likely villain. He would see the Hulk as a threat or a tool to be used for his own evil purposes. He might try to control the Hulk's mind or use dark magic to make the Hulk do his bidding.
One main theme is the clash and combination of different cultures. The military discipline and technology - based world of the Clone Commander meets the magic - filled and somewhat archaic world of Harry Potter. Another theme is often friendship. As the Clone Commander interacts with the characters in the Harry Potter universe, they form bonds and friendships.