Most likely, there will be trainers. They could be young and enthusiastic about Pokemon. For example, a boy trainer who has been on a long journey and finally meets his childhood friend who is also a trainer.
There might be a Pokemon as a main character too. Say a Pikachu that got lost from its trainer. The Pikachu could be the focus as it tries to find its way back to the trainer, and during this process, it meets other Pokemon and has all sorts of adventures. When they are reunited at last, it's a big celebration.
Another possibility is that there are two rival trainers. They were once enemies but then something happened that made them realize they need to work together. They get separated during this journey of self - discovery, but in the end, they reunite and become friends. Their Pokemon also play important roles in this transformation.
Obviously, Ash would be the main character since he's the one collapsing. His Pikachu would most likely be a key character as well. Pikachu is always by Ash's side and would probably be very concerned and try to help when Ash collapses.
Obviously, Paul would be a central character, even though he's dead. His friends and rivals are likely to be main characters too. For instance, Ash, who has interacted with Paul multiple times, would probably play a significant role. His Pokemon could also be important characters in a way, as they are left without their trainer. Other trainers in the Pokemon world who knew Paul, like Dawn or Brock if they had a connection to him, might also be main characters as they deal with the aftermath of his death.
It could be two elegant - looking Pokemon like Gardevoir and Milotic. Gardevoir has a very graceful appearance and psychic powers, and Milotic is known for its beauty and elegance in the water.
Most probably, the main characters would include enthusiastic trainers of different ages. There might be a budding trainer who is shy but has a very powerful Pokemon. Another could be an experienced trainer who acts as a mentor to the younger ones at the camp. And of course, there could be a mischievous trainer who always gets into trouble but has a heart of gold.
It could be about two trainers who were separated long ago finally meeting again. Maybe they were friends as kids and got separated during a Pokemon journey. Now they reunite and their Pokemon also have an exciting interaction.
Most likely the main characters would be the ones from the original 'it started with a kiss' series. They would be the ones whose relationship started with that kiss and are now facing 'the last kiss' situation.
Obviously, Naruto would be the main character since it's about him being the last male. But other characters like Sakura, Hinata, and Tsunade would also be important. They would play roles in either protecting Naruto or dealing with the situation his existence creates.
Obviously, Harry would be the main character as the title says he's the one who finds the Pokemon egg. His friends Hermione and Ron would probably be important characters too. They are always by Harry's side in most of his adventures in the wizarding world, so it's likely they'll be involved in this strange new discovery as well. And, of course, the Pokemon that hatches from the egg would also be a key character.
It could be a group of friends. Each friend might have a different reaction to the pokemon showing up in real life. One could be super excited and want to catch them all, another might be more cautious and worried about the potential dangers. Together, they would navigate the new world where pokemon and humans meet, having adventures and learning important lessons along the way.
The main characters would surely include Ash. In Pokemon Red, the rival character, Gary (or whatever name you choose for the rival in the game), could also play a major role. And of course, the various gym leaders from Pokemon Red. They could have different encounters with Ash, some might be friendly and help him, while others could be more challenging opponents. Also, Professor Oak might be involved, as he is connected to both Ash's world and the world of Pokemon Red in some ways.