The ponies' reactions would vary greatly. Rarity might be fascinated by Optimus Prime's design and might even try to make some sort of fashionable accessory inspired by him. Applejack would be more practical and would wonder what he was doing in Equestria and if he had any good intentions. Optimus would see the ponies as a new and interesting species. He would be patient with their initial wariness of him and would try to show them that he means no harm. He might also be a bit taken aback by their colorful and somewhat chaotic world compared to the more structured world of the Autobots.
The characters in One Piece and Sonic are very different. Sonic is a heroic hedgehog from a modern - ish world, while the One Piece characters are pirates, marines, and various other fantastical beings. When they meet, there could be a lot of misunderstandings at first. For example, Sonic might not understand the concept of the Pirate King right away. And the One Piece characters might be freaked out by Sonic's non - human appearance. But as they get to know each other, they would find common ground. Sonic could help the Straw Hat Pirates in their adventures with his speed, and the pirates could introduce Sonic to the wonders of their world, like the different islands and the secrets of the Grand Line.
The heroes in MHA would likely be initially shocked and a bit intimidated by the Doom Slayer. His brutal and direct approach to combat is very different from their more heroic and often rule - bound ways. Bakugo might be one of the first to be both intrigued and challenged by the Slayer's presence, as he respects power. The villains, on the other hand, would probably see the Doom Slayer as a major threat and might try to avoid direct confrontation at first.
Batman would find the world of Death Note very disturbing. The concept of the Death Note and the power it holds over life and death is something that goes against his sense of justice. He would be on a mission to stop anyone from misusing it. On the other hand, Light from Death Note might see Batman as a threat to his grand plan. Batman's reputation for thwarting criminals would make Light view him as someone who could expose his secret and put an end to his 'new world' vision.
The Naruto characters would be shocked by the brutality and hopelessness of the Walking Dead world. Naruto, with his positive attitude, might try to inspire the survivors to keep fighting. The Walking Dead characters, on the other hand, would be in awe of the Naruto characters' powers. Rick might see Naruto as a potential leader with his ability to bring people together. Daryl would probably be interested in learning how to use a weapon like a kunai or shuriken.
The wizards from Harry Potter would be in awe of Narnia's magical creatures. Harry, for instance, would be fascinated by Aslan. He'd probably see Aslan as a powerful and wise being, much like Dumbledore. On the other hand, the Narnians might be a bit scared of some of the dark magic in the Harry Potter world. For example, the Dementors would be a terrifying sight for them.
Fenris would likely be both impressed and a bit cautious of the Elf Inquisitor's abilities. His own lyrium - infused powers are quite different from the Inquisitor's magic or combat skills. He might see the Inquisitor's ability to control the elements, for example, as a powerful but also potentially dangerous force. The Inquisitor, on the other hand, would be curious about Fenris's lyrium markings and his superhuman strength and speed. They might initially test each other's limits in a non - hostile way, like during a sparring session.
I recommend "The Evil Concubine Bewitching the World's Defiant Spirit Talker". The female protagonist of this novel is a god-level spirit talker who can say that all things can be broken and that no one can live after death. However, she fell because of an accident and became a waste. However, the female protagonist did not give up on herself. She relied on the power of her voice and the ability to control heaven and earth to rise again. In the end, she became an unstoppable existence. The male lead was a mysterious and cold person. The process of the female lead and him getting along was full of mystery and brilliance. I hope you like this fairy's recommendation. Muah ~😗
Hermione would likely be devastated. She might go into a deep state of mourning, but also use her intelligence to try and figure out what led to Harry's death. Ron would be angry and heartbroken at the same time. He'd probably want to seek revenge if there was someone or something responsible.