Loki would likely interact with Pokemon trainers in a rather devious way. He might trick them into giving up their Pokemon or their valuable items. For example, he could pretend to be a lost traveler in need of help and then when the trainer gets close, he'd pull a fast one on them.
On the other hand, Loki could also form temporary alliances with some trainers if it serves his own interests. He'd be the kind of ally that you can't fully trust though. He might help a trainer win a difficult battle, but only so he can later use that victory for his own schemes, like getting access to a restricted area in the Pokemon world.
They would probably have to rely more on ground - type Pokemon for transportation. For instance, using Rapidash to run across long distances. Or they might use water - type Pokemon if there are waterways available in the no - fly zone.
In the hospital setting of a fanfiction, trainers would interact with their Pokemon in different ways. Some trainers could be using their Pokemon as emotional support for themselves while they visit sick friends or family. A trainer with a Snorlax might just sit beside it and feel comforted. Others would be guiding their Pokemon to do good deeds. For instance, a trainer with a Psyduck could be trying to get it to use its water - based attacks in a controlled way to help clean up small messes. Trainers would also be teaching their Pokemon proper hospital etiquette, like not running in the hallways.
One idea could be Loki somehow getting transported into the Pokemon world. He could use his trickery to outwit the Team Rocket - like stealing their plans and using them for his own amusement. Maybe he forms an unlikely alliance with a Pikachu that has a mischievous streak similar to his own.
In this fanfiction, Loki might interact most with Hulk. It would be an interesting dynamic as Loki is a master of manipulation and Hulk is, well, the Hulk. Loki could either try to use Hulk for his own purposes, which would be very dangerous, or he could end up on the wrong side of Hulk's anger. But at the same time, it could also lead to some unexpected moments of understanding or at least a begrudging respect between them.
He would probably interact a lot with Thor. Since they are brothers, there is a pre - existing relationship full of complexity. Also, he might interact with Iron Man quite often. Tony Stark's sarcastic nature and Loki's trickery could lead to some really interesting exchanges, either in the form of verbal sparring or working together on some high - tech and magic - combined projects.
Well, it could lead to some really interesting scenarios. They might gain the powers and abilities of the Pokemon they turn into. For example, a trainer who turns into a Pikachu could use Thunderbolt. And they would have to adapt to living as a Pokemon, like finding food in the wild and dealing with other Pokemon in a different way.
In fanfiction, Loki's interaction with the Avengers would be complex. He has a history of being an enemy, but also has moments of reluctant alliance. Sylvie, being a variant of Loki, would bring her own perspective. She might view the Avengers as symbols of the power structures she wants to undermine. Loki could be caught in between, trying to balance his new relationship with Sylvie and his past with the Avengers. The Avengers would be on guard, not fully trusting either of them.
Peter would likely be very cautious around Loki. He'd probably be using his Spider - Sense constantly. Loki would be his usual charming and devious self, trying to manipulate Peter. Maybe he'd offer Peter power or knowledge in exchange for something. Peter would be hesitant but intrigued.
He could use his Animagus form to communicate with Pokemon on a different level. For example, if he's a small and cute Animagus like a Pichu, Pokemon might be more likely to approach him and share secrets or lead him to hidden places.