Well, personally, I don't think characters in Smash Bros are sexualized. I mean, ok, there's been some upskirts screenshots in the past, but Samus is not there to be the ***** in thight suit, just a bounty hunter without her armor. Despite the Zero Suit, she still is a serious character.
I don't have to say how Zelda and Rosalina are simply elegant, and how Peach is just innocently cute (well, not according to some daily pictures, or the love triangle with Zelda/Link/Peach according to Sakurai
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). And Nana... Well it's Nana.
There's no reasons for Palutena to become a sex-appeal machine. There's even no reasons for Medusa's sideboob to become a sex-appeal machine