Could Pokémon3D become a MMO?
The long answer: This game is designed for single player and coop play with up to 3 other players (a total of 4 per game). It will not be a persistent world. However, that does not mean players will be limited to only battling, chatting and trading with people in the same coop game as them.
All multiplayer features are heavily under development and not finalized, but one thing is certain, this will not be a MMO.