This is just a list of anime with gender benders in them that Im putting here for sake keeping.
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-Ranma 1/2 is the most popular.
-Kampfer is one of my favorites, and it even counts as a magical girl anime too because it is one of the few
anime I know of where the male protagonist is TG'd because he receives a magic bracelet that gives a magical girl transformation. He even can control the transformation at will.
(he also gains the ability to shoot fire out of his hands in female form and he gets 3 other magical girls who are natural women by default who become both his team and his harem.)
-Im sure you've heard of Ore Twintail s