I was wondering if evolution is optional. I kinda like Oshawott and Snivy the way they are, and I kinda don't want to evolve them. Is it optional?
After a umm.... a certain event after the credits a screen will pop up saying "You and your partner can now evolve!" After that when either you or your partner level up in dungeon it'll say "Oshawott is trying to evolve into Dewott, is that okay?" YES, NO.
Source
The player decides whether to return or not and evolution may not happen until they return to Pokémon Paradise.
So evolution seems to be optional.
hope I helped!