In what games is it possible without trading to obtain the National Dex before the E4?

Question

And if you only need to trade one or two Pokemon, please mention those too.

Comments

In DPPt it's possible to get the national Pokedex without defeating the champion, but you do need to either battle her, trade, or talk to another player in the Underground.

Answer 1

Generation II
The player has the option to change it to the Old Pokédex order, which is available from the beginning.

Pokémon Ruby and Sapphire
In Pokémon Ruby and Sapphire, the Pokédex is upgraded with the National Mode after the game trades with FireRed, LeafGreen or Emerald.

Pokémon Diamond, Pearl, and Platinum
In Pokémon Diamond and Pearl, if the player has seen the first 150 Pokémon in the Sinnoh Pokédex, they can obtain the National Pokédex. In Pokémon Platinum, if the player has seen all 210 Pokémon in the expanded Sinnoh Pokédex, they can obtain the National Pokédex.

Pokémon Omega Ruby and Alpha Sapphire
In Omega Ruby and Alpha Sapphire, after the player has defeated or caught the super-ancient Pokémon, if they talk to Professor Birch in his lab in Littleroot Town, he will upgrade the player's Pokédex with the National Pokédex.

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