Who could be Harry Potter's boxing trainer in a 'Harry Potter is a boxer' fanfiction?

Sirius Black could be a trainer. Sirius, being Harry's godfather, would be highly motivated to train Harry. He could use the time - turner to go back to a time when he was at his peak in terms of combat skills and pass on his knowledge to Harry, especially in the areas of dark - wizard fighting and survival skills.

Maybe it's a former Death Eater who has seen the error of his ways. He wants to atone for his past sins by training Harry to defeat Voldemort. He has inside knowledge of the dark side's tactics and uses this to make Harry a more formidable opponent.

Obviously, Harry Potter himself could be the main character. He has the skills and the popularity from the original series. Ron Weasley could also be a main character, maybe as Harry's trainer or his corner man in the boxing matches. Hermione might be involved as well, using her intelligence to strategize for Harry's boxing career.

In this fanfiction, Harry could be a boxer to raise money for the rebuilding of Hogwarts after the war. He travels to different wizarding communities to participate in boxing matches. Along his journey, he meets some old enemies who now also see the value in his cause. They form an unlikely alliance, and Harry's boxing skills become a symbol of unity and hope for the wizarding world.

It could be Hagrid. He has a lot of strength himself and might know some basic principles of building muscle. He could guide Harry on how to lift the heavy weights, using his own brute strength as an example.

He would probably have a very unique team. For example, he could have a Ninetales because of its magical and fox - like appearance, which might remind him of his Patronus. His training methods would likely be a mix of wizardry and traditional Pokemon training. He might use spells to heal his Pokemon or to enhance their abilities in battles.

Hermione would be a likely colleague. She's highly intelligent and could be teaching a subject like Ancient Runes or Arithmancy. Ron could also be there, perhaps as a flying instructor or teaching something related to magical creatures. Neville might be a Herbology professor, given his love and talent for that subject. Luna could be teaching something really unique, like the study of magical creatures that are often overlooked or misunderstood.

Hermione would definitely be one of his allies. She is smart and resourceful and would be able to help Harry navigate the new political and magical situations he faces as a prince. For example, she could research ancient laws and prophecies related to his new status.

Voldemort and his Death Eaters would still be the main enemies. But now, Harry's guns would pose a new threat to them. They might not be used to dealing with such Muggle - like weapons, even if they are magically enhanced.

In some fanfictions, it could be an original character created by the author. Maybe a witch who was the result of an affair that his father had before he married his mother. However, this is completely against the canon of the original books, but in the world of fanfiction, anything is possible.