Nordgens are player on the aucion-list. They are Nordeus generate and sold by Teams like "Unholy AC", "Unstoppable FC",... they haven't any stats (played games, goals,...). Normally they are available after serverreset (at my timezone, it's 4:30am) for up to 4 hours, depents on server. For each manager-level there are conditions for a "perfect" nordgen. For example, L5: 18y.o., 99% and costs 11,5mio. If he is also low on vage (around 200k), it's the perfect fast trainer.
The more they are away from this conditions, the less they are a fast trainer (sorry for wording... )

Fast Trainer: Is a player, who easily earned many skillpoints at old version: practice match up to 160 points (1,6 skillpoints) each. Average are ~120 points each. Take a look at post #311, last pic.

But I don't know, if they are needed anymore. With new version training and worldclass drill, every player gains enough %.