Pokémon: Wishes of Tomorrow: The water south of Shin-Tokyo opens
What opens up at this point in the game, and everything you can catch by now that you couldn't before.
✓ Celebi Island, Prototype Island and Ryuden Island. Purify at Celebi's shrine; show the first purified Pokémon to the professor's assistant and you get Fly.
Newly reachable
Newly catchable (14)
Absol
Azurill
Blastoise
Clefable
Dragonair
Empoleon
Kingdra
Lanturn
Mudkip
Politoed
Squirtle
Umbreon
Vaporeon
Wigglytuff