Pokémon: Who told him to come out of Pallet Town!

Traveling through the Pokémon world, Natsume obtains a Pokémon research system, earning rewards for researching special Pokémon. Thus, Natsume becomes a Pokémon development master: At the Viridian Gym—"Gi-Oh! You want me to fight Mewtwo? You're not human, are you? Fine, I'm not human either! Go, Sludge Rotom, use Explosion!" At the Hoenn Tournament—the legendary Pokémon guy: "Your Dugtrio used three Earthshakers in one go! Those are clearly three Dugtrios, you're cheating!" Natsume: "Bullshit! What's wrong with my Dugtrio having a split personality?" "Go, Tyranitar, use Intimidate!" "Tyranitar!! (If you dare win, my 100,000 minions will break your trainer's legs!!)" The protagonist travels with Ash, and it's planned that they will travel to all regions later. The protagonist is a Rotom development master—Poké Ball Rotom, Electric Toy Rotom, Mech Rotom...