I don't see many spammers in this, but when I do, my main's (War Tobi) tilt usually pulls me through whatever strife I encounter. It's pretty fun watching people spam Nagato's Asura Path and just stand in one spot and phase through it. Though I understand this isn't an option for people who don't main Tobi. Just keep on your toes and strife right and left, if you're low on health and they bust out his mega buster, just stay back and avoid the laser.
As far as Roushi goes, his jutsu has a bit of tracking but it is otherwise the same deal. However, not as powerful. Dodge and dash in before he has a chance to fire off another. If they are true to spamming, they will sub and try it again and soon they'll be out of subs.