Not sure if it was already mentioned but pokemon has pretty much everything you need to create a different world:

- decent split on quests (gyms)
- annoying rival with personality (blue)
- collectable items needed to progress (badges)
- long and fitting theme for final quest (pokemon league)
- a lot of space for new girls (gym leaders, monsters themselves)
- double and triple battles

The only real downside is probably length since it would have to take at least 10 quests at least which would make it the longest quest by far. Unless you'd split it in the half and make showdown with Team Rocket or something as first pokeworld definitive encounter.