...hang on, that sounds like pokemon.
SMT predates the first release of pokemon red/blue by 5 years, 9 if you count SMT's super-series Megami Tensei.
Unlike pokemon, with animal-like creatures and gym leaders with an elite 4+champion+(maybe a rival too) at the end, SMT features various mythological creatures, even extremely obsure ones, major gods as bosses, and a fight with the forces of YHVH or lucifer at the end depending on who you sided within in the game. before you try to simpify the games into good vs evil, alllow me to explain. It's more about law vs chaos, both are pushed to the extreme and neither are meant to be good options. Law wants the world to stop and people to be put in hugboxes/killed (depending on which game you're talking about). Chaos wants the world to be in a state of continous war and fighting, where only the strong can live. YHVH is not very nice in these games, in SMT1 he has japan nuked, and he generally seems rather insane, (not that Lucifer is any saner). You can take a neutral route, albeit it's usually rather hard to, and it often leads to you fighting BOTH final bosses.the series has alot of spin-offs, the most popular of which is persona, which is very, very different in terms of mood, gameplay, difficulty, and story to SMT
sorry for the over-explanation
Functionally impossible. You just can't do that.
Maybe when dfhack gets updated.
dang :/