Create unique physical traits. Maybe an Ultra Beast has a hidden ability that is only visible when it's in a certain mood, like glowing patterns on its body. Also, you could give it a special way of moving, like floating in a spiral pattern instead of walking.
Well, in a fanfic about the Pokemon Hall of Origin and Ultra Beasts, you can expect a wild adventure. The Hall of Origin is a very mysterious place in the Pokemon world. Ultra Beasts are strange and powerful creatures from another dimension. A fanfic might explore how a trainer gets involved with the Ultra Beasts near the Hall of Origin. Maybe they accidentally open a portal to the Ultra Beast's world while exploring the Hall. It could also show battles between the trainer's Pokemon and the Ultra Beasts, with unique strategies based on the Ultra Beasts' strange abilities.
One idea could be a story where a trainer accidentally bonds with an Ultra Beast during an Ultra Wormhole event. The trainer has to learn to communicate with it and protect it from those who want to use it for evil purposes.
Ultra Beasts can fit into the Pokemon Hall of Origin story in a fanfic by being the guardians of the Hall. Maybe they were placed there by some ancient power to protect the secrets within. So when the protagonist tries to enter the Hall of Origin, they have to face these Ultra Beasts.
I'm not sure specifically what the 'ultra 85 novel' is about as the name is rather unclear. It could be a novel with some unique or extreme elements related to the number 85, perhaps a code or something specific to the author or a particular genre. But without more context, it's hard to say.
Well, ultra short fiction is like a snapshot of a story. It condenses a plot, characters, and emotions into a tiny space. It's all about making a big impact with very little text.