Mario: Hatless Variants, F.L.U.D-equipped variant, and an ice-mario skin. Also, Punch-Out!!! Referee variant.
Luigi: Poltergyst 3000 Variant, hatless variants, and a Cosmic Luigi skin.
Robin: Variant with their hood up over their face, Grandmaster variant (I don't really like the Grandmaster appearance, but it feels noteworthy.)
Ike: Chrom Alternate Skin, Ranger alternate skin (For those not FE savy, that's just what he wore in Brawl. But keep the muscles, or we'll have hitbox problems.)
Peach: Daisy Alternate Skin, 'nough said.
Yoshi: Give the Dinosaur Dragon Thing a hat! Jeez... Perhaps a variant where he wears Mario's hat, Luigi's hat, and Wario's hat. (Mario 64 For The Win)
Sonic: Variant with a Tails plush toy backpack.
Shulk: Purple Vest Variant, as well as a variant with goggles on his head. Also, give the kid some more headwear from his game, like maybe a circlet.
Zelda: It needn't be said that she should definitely have alts based on the various incarnations of her (Sans Tetra for obvious reasons.). Also, give her a variant where she wears Link's hat. [Insert Lenny Face Here]
I'm sure there's more I'm too lazy to list.
Luigi: Poltergyst 3000 Variant, hatless variants, and a Cosmic Luigi skin.
Robin: Variant with their hood up over their face, Grandmaster variant (I don't really like the Grandmaster appearance, but it feels noteworthy.)
Ike: Chrom Alternate Skin, Ranger alternate skin (For those not FE savy, that's just what he wore in Brawl. But keep the muscles, or we'll have hitbox problems.)
Peach: Daisy Alternate Skin, 'nough said.
Yoshi: Give the Dinosaur Dragon Thing a hat! Jeez... Perhaps a variant where he wears Mario's hat, Luigi's hat, and Wario's hat. (Mario 64 For The Win)
Sonic: Variant with a Tails plush toy backpack.
Shulk: Purple Vest Variant, as well as a variant with goggles on his head. Also, give the kid some more headwear from his game, like maybe a circlet.
Zelda: It needn't be said that she should definitely have alts based on the various incarnations of her (Sans Tetra for obvious reasons.). Also, give her a variant where she wears Link's hat. [Insert Lenny Face Here]
I'm sure there's more I'm too lazy to list.