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The Toy Zone Research - The most Disproportionately Popular Pokémon in Every Country
That is, Flamingos are animals present in countries such as Bolivia, Chile, Argentina and Uruguay, as well as in the nation that colonized these regions, Spain. I believe, therefore, that it is not strange that they would appreciate the introduction of a Pokémon of this type.
On the other hand, I don't know if Flamigo is a popular Pokémon in these places, what the research shows is that it is more popular in Paraguay than in the vast majority of other countries, and not how popular it is.