Just because someone calls themselves a trainer does not mean they have the prerequisite knowledge for safe AAS use. These guys obviously do not. Use an AI on cycle (assuming supraphysiological doses being used) unless you want the estrogen levels of a female. High estrogen levels have many deleterious internal side effect beyond gyno. When it comes to HCG I'll say this: Is there any other body part you'd be willing to let whither away? I doubt it. The use of HCG maintains testicular function and helps with other downstream hormone production as well as making restarting easier.
Clomid and Nolva are for pct. They are not AI's and do not serve the same purpose. They will do nothing to prevent the rise of estrogen levels.
Your friends are in serious need of some self-education.