Fox Sonic is 50:50 to me. Tbh, If I was giving anyone an edge I'd give it to sonic, and its only because he has more better stages than fox does imo. Any stage that has small blaster zones on the sides is great for him because of back throw. Real easy kills. Other then that, both characters can punish the other hard for mistakes. I personally like battlefield and FD for the matchup, battlefield being my goto if I have the choice. I ban smashville and castle siege against sonic most of the time. Delfino is another option to ban, but fox gets hilariously early kill gimmicks off the top of the transitions, while sonic gets the back throw gimmicks on the walk offs. So if Sonic takes you there, he's giving you an early kill option too in exchange for his. Not to mention he really can't kill early with backthrow on the island parts.