Blessed Otherworld Odyssey: Boundless Ascension

On the cusp of his world evolving, Jason and the rest of humanity find themselves on the verge of being expelled to a place called the Tutorial. Before the transfer can take place, Jason finds himself being attacked by a fish that had evolved under the influence of Mana. He's able to defeat it, but when he next awakens, he finds himself in a dark void between dimensions—a subdimension that's all his own. Now, while waiting for his world to open, Jason seeks to reunite with those he's obliged to while traversing familiar but different worlds whose influence manifested in his world as popular media. His first destination is the world of Pokémon, but while many elements remain the same, it is very different from the kids-friendly franchise he knew and loved. — Description from novelcodex.org