For Peter Parker/Spider-Man: Brown khaki pants with a plain white T-shirt and blue flannel shirt will make this ordinary Spider-Man look come to life. Add a backpack and white sneakers to really get in character. Oh, and if you want to look like Spider-Man in action, that will require the head-to-toe ensemble.
For MJ: This character wears cute and casual outfits for most scenes. Copy her look by wearing a graphic tee, a black cardigan, and jeans.