Peach's design is just a concept. Might change later in development. Her dress is meant to resemble Olive Otter's outfit in Shipwrecked 64, but Peach's dress looks more like a candy cane or something at least to me.

Yoshi's design is meant to be the one seen in Super Mario Sunshine as Yoshis come in different colors, so I wanted to make my fan game unique by having a different colored Yoshi than the usual green one seen in FNAW 3 and FSAW and other FNAW fan games that I know of. I was gonna make renders of them but I got lazy and also because my laptop is at 13%