In the games, given enough effort and time, a player can get Pokémon with better stats and alternate color palettes, and are highly valued by players. Additionally, there is a built-in function that allows players to offer certain Pokémon in exchange for others. Often, players using this function will offer higher value Pokémon for other similarly rare Pokémon. For a lot of people, paying for these Pokémon might actually seem to be more efficient.
My question is purely hypothetical and I have no desire to do this, but if I started working in my games to legitimately generate these more valuable Pokémon, could I legally sell them online? More generally, is selling digitally generated goods legal?
I debated putting this question on Arqade, but I figured I might get more in depth answers on Law.