Pokéflute Playtime Sequel

After a playthrough of Let's Go Pikachu, I had an idea for a sequel. Like my Fusion World, it would mix the anime, games, and manga, but in a more fluid way than just throwing all the characters into the same world.

The idea is to have the story take place after everything's said and done, but with slight differences. Like in Let's Go, the characters have been through their arcs and Ash is Pokémon Monarch, but the evil teams still need stopping. There's just two things I'm wondering is.

1) Should I use the Let's Go Trio in these alternate stories, or three completely new OCs?

2) Let's Go used the manga as inspiration for Red, Blue, and Green's teams. With that fact: should I use the manga names for the characters, or still use the game name?