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The National Dex has widely been speculated about in the means of obtaining it. Some people thought e-cards, some people thought its actually in the game. Well now I will Quelch all rumours as we have the actual way to get the National Dex in Ruby/Sapphire.

It's simple, all you have to do is trade with Fire Red/Leaf Green and it automatically goes into your game on the first trade. It is that simple