Game story idee
Underneath the beginner town there is a pool (important later)
Somewhere in the world map there is a building where you can find the Lewd Virus Monster Trainer rangers
When you go to talk to one of the rangers you, you get told that they are having a few problems with ranger shortage they want you to help them by doing quest where one of them is going to the pool and save a “Eevee” ones you save the “eevee” it is so happy it turns into a “Vaporeon” ant wants to stay with you. Afterwords the rangers agree you can keep the “Vaporion”
The saving mechanic can be throwing a “Lewd Virus Monster Trainer”ranger-ball on a specific creature (witch name not gone name for reasons)
afterwords bring it to the rangers and than you get cash or somthing else