The roles dont need to be banned, they just need to be worked around.
My Conclusion:
Rework Jailor to be on-par level wise with Mayor.
Make a Town(Leader) Slot like I have suggested before, this would remove randomness to powerful town roles that can easily carry, and to the 1 town that will carry, they will still need cooperation from other roles, just as ti posting daily, escort using their abilities to figure out who the RM are, TK shooting mafia to keep the Town Mafia ratio at a 2:1.5 at night, etc. (Link in signature)
Transporter is the most theoretically balanced role, but practically unbalanced.
It excels in what does, as long as the person playing Transporter isnt that good at knowing what to do.
The thing is, their is no appropriate nerf to Transporter's confirmability or ability that will work effecitvely, therefor a rework is required.
Ambusher can be buffed, but it would have to be a very specific buff to not increase its potential kpn, but rather increases its likely hood of picking of required outsiders.