I have a feeling the alts are just gonna be reskins referencing the eight main party members - Joker, Ryuji, Morgana, Yusuke, Makoto, Futaba, and Haru.
However, I feel like there’s just so much more that you could do. After all, there are so many outfits available in the game, and so many colorful characters that it’s hard to capture all of that into eight costumes.
With all of this in mind, this was the best job I could do with referencing most of the main cast, while also having alts that are interesting, unique, and properly reference Joker and Persona 5 as a whole.
Default
Yellow shirt, black coat and pants, yellow gloves, blonde hair, black mask. Reference to both Skull and Mona. Also a nod to Persona 4’s color scheme.
White shirt, dark blue coat, black pants, bright blue gloves, brown hair, white mask. Reference to Fox and Queen.
Red shirt, white coat, white pants, red gloves, white hair, red mask. Reference to Panther and Crow, as well as a sort of inverse of Joker’s default.
Pink shirt, white coat, tan pants, pink gloves, light brown hair, black mask. Reference to both Sojiro and Noir.
Green shirt, black coat and pants, lime green gloves, orange hair, green mask. Reference to Oracle.
Winter school uniform.
Velvet room attendant.
The last two would be costumes, opposed to recolors, of course. I feel like it’s definitely important to have the school uniform, considering it’s Joker’s main outfit for about half of the game. I also think that with the consistent themes of justice, imprisonment, breaking free, and so on, along with Joker just straight up being jailed a lot, having a prisoner outfit would make sense.