Everyone Tames Beasts, but I Got a Pokémon Master System

In a world where everyone trains beasts, he gets a Pokémon Master System. [Host, choose your Starter Pokémon: Charmander, Squirtle, or Bulbasaur.] Su Yu hears the System's prompt ring out in his mind and stares blankly at the beast pets in front of him. Bite Tortoise and Squirtle are both turtles, and if you really stretch it, lizards could be related to Western dragons... But what’s with the frog?! Since when is Bulbasaur a frog?! Mega Evolution, Z-Moves, Dynamax, Terastallization... Watch Su Yu take an unconventional path in beast training and gradually rise to become the Beast Taming King.