

It is very difficult for every Pokémon to have a niche if many Pokémon with the same (mono)typing exist with these regional forms, every Pokémon is unique. Every type combination is distributed at least once.

Around 50% of fully evolved Pokémon have regional forms so there will be a lot of surprises if you play blind. All Pokémon with changed typings have an adjusted color palette that indicates the type change.

Some dual types also received a type change. All fully evolved monotype Pokémon in Platinum received a regional form with an additional typing. To ensure that no two Pokémon have the exact same purpose, there are no fully evolved monotype Pokémon in Platinum Redux.
