I am currently working on developing some of our employees to become good Trainers, they will mainly be training our new comers. I don't think if giving them a Train the Trainer training workshop will be enough. Do you think a pre exam can me arranged or be of any good, or should I just follow the recommendation of their Managers?

Hi Icey,
Grooming trainers is a continuous process. especially if someone is new to training a mere TTT will not be sufficient.
A proper training track with a blend of initial assessment, TTT, post session assessment and a coaching / handholding schedule can groom a non trainer into good trainer