One great 'Harry Potter Fanfiction Scooby Gang Fanfic' could be 'The Mystery at Hogwarts'. In this fic, the Scooby Gang somehow finds themselves transported to Hogwarts. They team up with Harry and his friends to solve a mystery that involves both magic and some spooky elements that the Scooby Gang is used to. It's really interesting to see how the two groups interact and how the Scooby Gang's detective skills are put to use in the magical world.
A theme that is often seen is the idea of adapting to new situations. The Scooby Gang has to quickly get used to the magic around them, and the Harry Potter characters have to deal with the Scooby Gang's unorthodox methods of investigation. This creates a lot of interesting scenarios where characters grow and learn from each other as they try to adapt to the new circumstances they find themselves in.
Harry's gang could include some of the characters we don't see much of in the original books. For example, the house - elves. Dobby was already very loyal to Harry. Maybe he could convince other house - elves to help out in a more active way. There could also be some of the older students who dropped out of Hogwarts for various reasons but still have a lot of magical knowledge. And of course, Hagrid could be an honorary member, providing his vast knowledge of magical creatures and his big - hearted support for Harry and the gang.
A really cool one is 'Potter's Posse'. In this fanfiction, the gang members are shown to be involved in solving some mysteries within Hogwarts that the teachers are oblivious to. It's a fun read as it has elements of mystery, friendship and magic all intertwined. The characterizations are quite accurate to the original books, which makes it a great read for any Harry Potter fan.
Harry himself would be one of the main members, of course. Hermione could also be part of it, using her vast knowledge of magic to the gang's advantage. Neville might join too, having proven his courage time and time again. And perhaps some of the Weasley twins' friends from their pranking escapades.
One great 'Harry Potter Westworld fanfic' could be one where the characters from Harry Potter are transported into the Westworld universe. They might have to figure out the rules of this new world full of hosts and hidden agendas. Another interesting one could be where the technology of Westworld is introduced to the wizarding world, causing all kinds of chaos and new opportunities for magic - related problem - solving.
The plot might involve Harry being part of a gang that is formed to protect the Muggle - born students. They operate in the shadows, using their combined skills to counter any threats from the pure - blood supremacist groups. They could be led by an older student who has seen the discrimination first - hand and is determined to stop it.
In a fanfiction where Harry Potter joins a gang, it could lead to a whole new set of adventures. The gang might be involved in some underground wizarding activities, like illegal potion - making or trading in dark artifacts. Harry, being part of it, would be caught in a web of danger. He would have to navigate between his new 'friends' in the gang and his old friends from Hogwarts. This could create a great internal conflict within him as he tries to figure out who he really wants to be and what kind of wizard he wants to grow into.
One possible goal could be to protect the wizarding world from new and unknown threats. Since Harry has always been a defender, his gang would follow suit. Another goal might be to promote unity among different wizarding groups. In the original series, there were some divides, but as a leader, Harry could aim to bridge those gaps through his gang.
It really depends on the specific fanfic. Different writers might have their own takes on when this meeting occurs.
I've read a piece of fanfiction titled 'The Kryptonian and the Gryffindor'. This one has a really unique take on the crossover. It starts with Superman being drawn to the magic of Hogwarts for some mysterious reason. As the story progresses, we see the friendship develop between him and Harry Potter. The author does a great job of showing how their different powers and personalities complement each other while they face various challenges together.