lol @ KID not being able to read this Lucas' troubled english... it's not even that bad; he's just being internet-sloppy.
Marth's not a bad matchup for Sonic. I used to think it was
miserable, that there was nothing we could do about Marth. But pretty much all the major Sonics think that Marth is even at worst, iirc.
Unlike most matchups, Marfa can't force you to approach. No projectile. We can camp him, we can run away, we can just dilly-dally until he messes up, and we're fast enough to be able to punish it.... unless the Marfa is good. He'll do his baiting, to get you to come close when he's prepared to strike... but you just need to learn when to get in and when to get out.
Be very very wary of trying to gimp a Marth. But definitely get him offstage and it reduces his options. If you're unpredictable with how you deal with him offstage it will help a lot (ex. don't just spam Springs at him, also don't predictably try to Bair him while he's about to up-B snap to the ledge). But if you can instant-edgehog with Sonic then there will definitely be times when you can net easy kills that way.
Definitely watch out for his up-B OoS.