Mashmyre created all the Verses, which makes him 2-C, he created Oasis as well, which can do a bunch of crazy stuff as well
Genesis uses the power of Oasis, Oasis isn't just the island, it's described to be the sea, the sky, the people, and the whole world in fact, once Oasis was destroyed, the island, people, sky and the entire world was erased as if was nothing, and everyone gets sent back to their worlds, it should also be known that Oasis's power as been described as infinite multiple times, which on its own would just be Hyperbole, but it has actual feats to back it up, plus the power of Oasis leaked into other worlds, meaning that Oasis can create and destroy worlds
Point being, Mashmyre is definitely 2-C for creating Fairy Tail, Rave, and Edens Zero which all have multiple Timelines and Universes within there stories
Genesis who uses Oasis should scale to 5-B, we assume the world that was created is just a Planet, we see no stars in the sky, or even a moon or sun, all we know is that it is a planet as stated by Rebecca, the Oasis created the Planet and can destroy it as a mere thought as well, it is also a world that is linked to all the other ones
This of course has no impact on the actual verses at all, so there's no outliers or scaling issues here, this is purely self contained, meaning the 3 protags who fought and damaged Genesis also scale to Oasis which again is at least Planet level, it would be like how there is Xeno Goku which is way stronger but completely separate from canon Goku
So we can have separate 5-B Trio of Hero Profiles