This pack uses Optifine random entities to add zombie skins based on the fighters in Super Smash Bros Ultimate. The zombies can spawn randomly alongside the default, or you can name them to guarantee the one you want (the name must be exactly as specified below). Note that this pack doesn't include every single fighter, just the humanoid ones that wear clothes (Pants specifically are required).

Here's a list of all the zombies' names:
64: Mario, Builder Mario, Link, Hero Link, Dark Link, Samus, Dark Samus, Fox, Luigi, Ness (only works on baby zombies), Captain Falcon
MELEE: Peach, Daisy, Popo, Nana, Sheik, Zelda, Dr. Mario, Falco, Marth, Lucina, Young Link (baby exclusive), Ganondorf, Roy, Chrom
BRAWL: Pit, Dark Pit, Zero Suit Samus, Casual Zero Suit Samus, Wario, Plumber Wario, Snake, Ike, Hero Ike, Pokemon Trainer, Pokemon Trainer!F, Lucas (baby exclusive), King Dedede, Olimar, Alph, Toon Link (Previous 3 are baby exclusive), Wolf
SMASH 4: Villager, Villager!F, Mega Man, Wii Fit Trainer, Wii Fit Trainer!M, Rosalina, Little Mac, Hoodie Little Mac, Mii Brawler, Mii Swordfighter, Mii Gunner, Palutena, Robin, Robin!F, Shulk, Ecru Shulk, Ryu, Ken, Cloud, Advent Cloud, Corrin, Corrin!F, Bayonetta, Bayonetta 1 (Terrible name, I know. If y'all have suggestions I'd love to hear them)
ULTIMATE: Inkling, Blue Inkling, Yellow Inkling, Green Inkling, Magenta Inkling, Cyan Inkling, Violet Inkling, Indigo Inkling (All inklings are baby exclusive), Simon, Richter, Isabelle, Winter Isabelle
FIGHTER PASS 1: Joker, Academy Joker, Luminary, Erdrick, Solo, Eight, Banjo, Terry, Byleth, Byleth!F
FIGHTER PASS 2: Min Min, Steve, Alex, Sephiroth, Shirtless Sephiroth, Pyra, Mythra, Kazuya, Suit Kazuya, Devil Kazuya, Suit Devil Kazuya, Sora, Timeless River Sora