Sorry, but it was terrible from a coding, balance, and gameplay perspective, which is why it's dead. The Pokémon Trainer took the time of roughly 5 newcomers because it made the programmers, aka the most important people, super busy for a super long time.
Plus, the character switching mechanic was boring, dumb, buggy (you know the loading screen=??? Depending on how long it took depended upon how long the transformation switch for transformation characters took) and hindered the uniqueness of the individual characters that were a part of it.
That's why we'll never see those abominations or the likes of say Diddy/Dixie again, and why good ideas like K. Rool will reign supreme.