Very nice, I like how you even gave the characters, and objects their original limited color palettes like the original NES game. I also noticed these look like levels 1-1, and 8-4, the first & last levels of the game.
The brick details look a bit to small on the "castle level," but on the other hand, that kinda goes along with the "paper cut-out" style the Paper Mario games tend to have.
They seemed to like red and dark tan a lot back then. I love the retro Peach. I think red and white doesn't clash but actually is bold and expressive, whereas pink and fushia just kind of... are what you'd expect.