OK, pit can be a tough matchup no doubt, but there are ways around him:
First things first, your bair, and your fair are your best aerials in the fight no matter what. Abuse the back aerial for kills, and get in close with the fair, which can also kill him as well. Your only use for your shine in this match would be to stun and go for a quick damage rack up, since his arrows fly faster then you can put up your shine( unless you can predict it). shield dashing to me is a good way to stop his arrows, and get close for maybe an f-smash or f-tilt. Nair into him followed by a shine then f-tilt for some sheild stab and damage. Once this guys off the edge, spam your blaster. SH blaster him until he trys to go either for the edge or above you, if he goes for the edge, hug the edge, drop down and backair or dair(if your confidant) to his death. When your off the edge, use your telestepping and "scarring"(if possible on that stage) to get back safely without dealing with pit to much. If you need that quick kill, Nair into a auto dodge foloowed by an d-smash to take him out at 90-120% of damage. So far, I've only played a few pits, and that's what I used against them. Im sure their are other players here with some more advice, but for now here's mine buddy.
Wish you luck against pit.