I personally think that Roth only needed 1 traitor, someone very close that Michael would not expect. He knew, the more traitors there are, the more of a chance Mike would find out,
But Fredo atleast needed a team to pull this off. He would for sure need some members of the compound's security staff, which is headed by Rocco.
Of course, most of us in here would tell you there is no way that weak and stupid Fredo could have orchestrated ALL of this by himself. i.e-slicing the assassins throats, drapes, etc
