Before the match begins, you start off with pressing a specific combination of buttons during the countdown. Each different input has a number; the value of all the numbers from the buttons you hold down determines which skin you get. You can also preview all of the skins during the playtest in the character selection.

(A)ttack: 1
(Sp)ecial: 2
(St)rong: 4
(J)ump: 8
(D)odge: 16
(T)aunt: 32

[0] White
[1] (A) Temmel
[2] (Sp) (The Melancholy of) Haruhi Suzumya
[3] (A Sp) Lucario (Pokemon)
[4] (St) Tails the Fox (Sonic)
[5] (A St) Wolf O' Donnell (Starfox)
[6] (Sp St) Dio Brando (Is this a jo jos reference?)
[7] (A Sp St) Peach (Mario)
[8] (J) Ashley (Wario)
[9] (A J) Kumatora (EarthBound)
[10] (Sp J) Whinnie the Pooh
[11] (A Sp J) The Joker (Bat Man)
[12] (St J) Little Mac (Punch-Out)
[13] (A St J) Hatsune Miku
[14] (Sp St J) Linne (UNIST)
[15] (A Sp St J) Carmelita Fox (Sly Cooper)
[16] (D) Amaterasu (Okami)
[17] (A D) Fox McCloud (StarFox)
[18] (Sp D) Absa (RoA)
[19] (A Sp D) Acid Rainbows (Workshop)
[20] (St D) Zerra (Workshop)
[21] (A St D) Rayman
[22] (Sp St D) Strider Hiryu (Strider)
[23] (A Sp St D) Frisk (Undertale)
[24] (J D) Conker (Bad fur day)
[25] (A J D) Mettaton (Undertale)
[26] (Sp J D) Zero suit Samus (Metroid)
[27] (A Sp J D) Velma Dinkley (Sooby-Doo)
[28] (St J D) Astra (Workshop)
[29] (A St J D) Pomme (Workshop)
[30] (Sp St J D) Wii Fit Trainer
[31] (A Sp St J D) R-00 (Workshop)
[32] (T) Hit-or-miss Girl (Tik-Tok)
[33] (A T) Sly Cooper
[34] (Sp T) Abyss (RoA)
[35] (A Sp T) Hilary (Beyblade?)
[36] (St T) Neuromance (Krunker.io)
[37] (A St T) Rosa (Pokemon)
[38] (Sp St T) Eevee (Pokemon)
[39] (A Sp St T) Amy Rose (Sonic)
[40] (J T) Sally Acorn (Sonic)
[41] (A J T) Tangle (IDW Sonic)
[42] (Sp J T) Spectrum (Krunker.io)
[43] (A Sp J T) Linkle (Legend of Zelda)
[44] (St J T) Renamon (Digimon)
[45] (A St J T) Donkey Kong
[46] (Sp St J T) Papyrus (Undertale)
[47] (A Sp St J T) Undyne (Undertale)
[48] (D T) Siren (Workshop)
[49] (A D T) Nicole the Hologram (Sonic)
[50] (Sp D T) Shantae (Half Genie)
[51] (A Sp D T) Krystal (Starfox)
[52] (St D T) Mikuru Asahina (The Melancholy of Haruhi Suzumya)
[53] (A St D T) Itsuki Koizumi (The Melancholy of Haruhi Suzumya)
[54] (Sp St D T) Klonoa
[55] (A Sp St D T) Foxy (FNaF)
[56] (J D T) Brock (Pokemon)
[57] (A J D T) Mollo (Workshop)
[58] (Sp J D T) Penny (Workshop)
[59] (A Sp J D T) Shaymin (Pokemon)
[60] (St J D T) Delphox (Pokemon)
[61] (A St J D T) Raynb0w (Krunker.io)
[62] (Sp St J D T) Weiss Schnee (RWBY)
[63] (A Sp St J D T) Clairen (RoA)

I like to thank DBO for the grammar check, bbMrbanana and MasterAce 92 for finding some of the references of the skins, MeeM for testing the inputs out, and a big thanks to Lukaru for giving me permission to post this guide, and for making the original character.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1877715009