The Pokédex in Fire Red and Leaf Green is suprisingly more advance than in previous games.
In this new Pokédex you can select certain kinds of sorting for the Pokémon including Location where it will give you a list of all the locations, pick one and it'll show all Pokémon Seen and Caught in it (that you've seen)
You can also sort the Dex out by Pokéballs
However thats not all, when it has sorted the Pokédex out you can view the Pokémon and their evolution lines if they're catchable in the area as it would be on the same page
And Of Course, you can see the dex normally and/or pick the Pokémon in the sections and view their dex entries

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