One common strategy is deception. Harry could pretend to be compliant with the Ministry's rules while actually going against them. For example, if the Ministry is trying to restrict certain magical activities, Harry might do them in secret and make it seem like he's not involved.
In some fanfictions, Harry might use his knowledge of magic that the Ministry doesn't expect. For example, he could use ancient spells or charms he learned from old books. He may also outsmart the Ministry by using his friends' skills cleverly. If Hermione has some special knowledge about Ministry regulations, Harry could use that to his advantage.
One interesting strategy could be his use of misdirection. He might make others think he's going one way while actually doing something completely different. This keeps his opponents guessing.
It can be. Fanfiction often subverts the traditional power dynamics. Harry, having grown up in a different environment than Dumbledore, might have a different perspective on magic. He could use his street - smart nature, gained from his years with the Dursleys, combined with his magical knowledge to come up with solutions that Dumbledore wouldn't think of. Also, his bond with his friends could give him an advantage in certain situations where Dumbledore might act more alone.
A common plot device is misdirection. Harry might create a false lead or distraction that makes Snape focus on the wrong thing. For example, he could stage a minor 'accident' in the corridor that draws Snape's attention while he slips away to do something else he's not supposed to. Another device is using his friends' unique abilities. If Hermione has found a loophole in a rule, Harry can use that knowledge to outmaneuver Snape who is always strict about the rules.
In some fanfictions, Harry might outsmart Umbridge by using his knowledge of magic in unexpected ways. For example, he could use spells that are not commonly known to get around her rules. Maybe he uses a charm to make her quill write false reports, thus confusing her when she tries to use those reports against him.
In some fanfictions, Harry might use his knowledge of magic in unexpected ways. For example, he could combine spells in a new and creative manner that others haven't thought of. This gives him an edge over everyone.
Harry might outsmart Dumbledore by having a deeper understanding of the Horcruxes. If he discovers something new about Horcruxes that Dumbledore missed, perhaps a hidden weakness or a way to detect them more easily. This could give him an upper hand, especially since the Horcruxes were such a crucial part of the battle against Voldemort.
One possible reason could be the Ministry's corruption. In the original series, the Ministry often showed signs of being influenced by dark forces or being overly bureaucratic and not seeing the real threats. So in the fanfiction, this might be a driving factor for Harry to oppose them.
Well, it could be about Harry Potter using common sense in various situations that are not exactly as depicted in the original books. Maybe it shows him making practical decisions during his adventures at Hogwarts or while facing Voldemort.
He could use his magical abilities in a creative way. Maybe he performs a spell that reveals the truth, something like a Veritaserum - like spell but not as unethical. This could force the real culprits to confess or make the false accusations fall apart. Another strategy is to have Dumbledore or other respected wizards vouch for him. Their credibility could sway the court in his favor.