In case anyone else was as curious about this as me, here's a complete look at the genders of all Smash characters.

Note: The characters' genders listed here are taken from the Smash games and blogs, and are not necessarily their canonical genders from their source games.

Several characters on the roster don't fall strictly into "male" or "female," so I divided them into five categories:

Male - Characters referred to using male pronouns by official Smash blogs

Female - Characters referred to using female pronouns by official Smash blogs

Selectable - Characters with both male and female skins

Ambiguous/Genderless - Characters referred to only in gender-neutral terms by official Smash blogs

Both - Characters consisting of multiple characters, one male and one female

Game-by-game breakdown

https://i.imgur.com/pWT5gmU.png

Smash 64: 9 Male, 1 Female, 2 Ambiguous

Melee: 17 Male, 4 Female, 4 Ambiguous, 1 Both

Brawl: 28 Male, 5 Female, 3 Ambiguous, 1 Both

3DS/Wii U: 36 Male, 9 Female, 8 Selectable, 7 Ambiguous

Ultimate: 43 Male, 12 Female, 11 Selectable, 8 Ambiguous, 1 Both

The Full List

Male

• Mario
• Donkey Kong
• Link
• Yoshi
• Kirby
• Fox
• Luigi
• Ness
• Captain Falcon
• Bowser
• Dr. Mario
• Falco
• Marth
• Young Link
• Ganondorf
• Roy
• Chrom
• Mr. Game & Watch
• Meta Knight
• Pit
• Dark Pit
• Wario
• Snake
• Ike
• Diddy Kong
• Lucas
• Sonic
• King Dedede
• Olimar
• R.O.B.
• Toon Link
• Wolf
• Mega Man
• Little Mac
• Pac-Man
• Shulk
• Ryu
• Ken
• Cloud
• Ridley
• Simon
• Richter
• King K. Rool

Female

• Samus
• Dark Samus
• Peach
• Daisy
• Sheik
• Zelda
• Lucina
• Zero Suit Samus
• Rosalina & Luma
• Palutena
• Bayonetta
• Isabelle

Selectable

• Pikachu
• Pokémon Trainer
• Villager
• Wii Fit Trainer
• Mii Brawler
• Mii Swordfighter
• Mii Gunner
• Robin
• Bowser Jr.
• Corrin
• Inkling

Ambiguous/Genderless

• Jigglypuff
• Pichu
• Mewtwo
• Lucario
• Greninja
• Duck Hunt
• Incineroar
• Piranha Plant

Both

• Ice Climbers

Interesting observations

• Brawl has the most male-dominated roster, even more than Smash 64. It only introduced 1 new female fighter, and she didn't even have her own spot on the CSS.
• No characters had selectable genders until Smash 4, and of the 11 characters with selectable genders, only 3 (Inkling, Wii Fit Trainer, Mii Gunner) are female by default.
• Every Pokémon (except for Pikachu's individual skins) is strictly referred to as "it," including ones that have been given implied genders by the Smash community (such as Jigglypuff and Lucario).
• On the other hand, some characters which could be considered ambiguous (such as R.O.B. and Yoshi) are always referred to as "he," so they are apparently male.
• Pikachu Libre's heart-shaped tail moved it from "ambiguous" to "selectable".
• Bowser Jr. also technically fits into the "selectable" category because of Wendy Koopa.