in some of the Pokemon episodes where their were butterfree, they weren't shiny but they had orange spots on the bottom of their wings but but some of them didn't have orange spots. whats with these spots?
Butterfree in the Orange Islands have differently colored wings as well as a different wing pattern as those seen in the mainland. This variant makes up the vast majority of the Butterfree population of the Orange Archipelago, with a small number of the Mainland variant living on one unnamed island.
It was one of the Orange Island Butterfree, which had a different color scheme probably due to the different food and habitat. Here's a pic:
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